1 /* 2 * OHCI HCD (Host Controller Driver) for USB. 3 * 4 * (C) Copyright 1999 Roman Weissgaerber <weissg@vienna.at> 5 * (C) Copyright 2000-2004 David Brownell <dbrownell@users.sourceforge.net> 6 * 7 * This file is licenced under GPL 8 */ 9 10 /*-------------------------------------------------------------------------*/ 11 12 /* 13 * OHCI Root Hub ... the nonsharable stuff 14 */ 15 16 #define dbg_port(hc,label,num,value) \ 17 ohci_dbg (hc, \ 18 "%s roothub.portstatus [%d] " \ 19 "= 0x%08x%s%s%s%s%s%s%s%s%s%s%s%s\n", \ 20 label, num, temp, \ 21 (temp & RH_PS_PRSC) ? " PRSC" : "", \ 22 (temp & RH_PS_OCIC) ? " OCIC" : "", \ 23 (temp & RH_PS_PSSC) ? " PSSC" : "", \ 24 (temp & RH_PS_PESC) ? " PESC" : "", \ 25 (temp & RH_PS_CSC) ? " CSC" : "", \ 26 \ 27 (temp & RH_PS_LSDA) ? " LSDA" : "", \ 28 (temp & RH_PS_PPS) ? " PPS" : "", \ 29 (temp & RH_PS_PRS) ? " PRS" : "", \ 30 (temp & RH_PS_POCI) ? " POCI" : "", \ 31 (temp & RH_PS_PSS) ? " PSS" : "", \ 32 \ 33 (temp & RH_PS_PES) ? " PES" : "", \ 34 (temp & RH_PS_CCS) ? " CCS" : "" \ 35 ); 36 37 /*-------------------------------------------------------------------------*/ 38 39 #if defined(CONFIG_USB_SUSPEND) || defined(CONFIG_PM) 40 41 #define OHCI_SCHED_ENABLES \ 42 (OHCI_CTRL_CLE|OHCI_CTRL_BLE|OHCI_CTRL_PLE|OHCI_CTRL_IE) 43 44 static void dl_done_list (struct ohci_hcd *, struct pt_regs *); 45 static void finish_unlinks (struct ohci_hcd *, u16 , struct pt_regs *); 46 static int ohci_restart (struct ohci_hcd *ohci); 47 48 static int ohci_hub_suspend (struct usb_hcd *hcd) 49 { 50 struct ohci_hcd *ohci = hcd_to_ohci (hcd); 51 int status = 0; 52 unsigned long flags; 53 54 spin_lock_irqsave (&ohci->lock, flags); 55 56 ohci->hc_control = ohci_readl (ohci, &ohci->regs->control); 57 switch (ohci->hc_control & OHCI_CTRL_HCFS) { 58 case OHCI_USB_RESUME: 59 ohci_dbg (ohci, "resume/suspend?\n"); 60 ohci->hc_control &= ~OHCI_CTRL_HCFS; 61 ohci->hc_control |= OHCI_USB_RESET; 62 ohci_writel (ohci, ohci->hc_control, &ohci->regs->control); 63 (void) ohci_readl (ohci, &ohci->regs->control); 64 /* FALL THROUGH */ 65 case OHCI_USB_RESET: 66 status = -EBUSY; 67 ohci_dbg (ohci, "needs reinit!\n"); 68 goto done; 69 case OHCI_USB_SUSPEND: 70 ohci_dbg (ohci, "already suspended\n"); 71 goto done; 72 } 73 ohci_dbg (ohci, "suspend root hub\n"); 74 75 /* First stop any processing */ 76 hcd->state = HC_STATE_QUIESCING; 77 if (ohci->hc_control & OHCI_SCHED_ENABLES) { 78 int limit; 79 80 ohci->hc_control &= ~OHCI_SCHED_ENABLES; 81 ohci_writel (ohci, ohci->hc_control, &ohci->regs->control); 82 ohci->hc_control = ohci_readl (ohci, &ohci->regs->control); 83 ohci_writel (ohci, OHCI_INTR_SF, &ohci->regs->intrstatus); 84 85 /* sched disables take effect on the next frame, 86 * then the last WDH could take 6+ msec 87 */ 88 ohci_dbg (ohci, "stopping schedules ...\n"); 89 limit = 2000; 90 while (limit > 0) { 91 udelay (250); 92 limit =- 250; 93 if (ohci_readl (ohci, &ohci->regs->intrstatus) 94 & OHCI_INTR_SF) 95 break; 96 } 97 dl_done_list (ohci, NULL); 98 mdelay (7); 99 } 100 dl_done_list (ohci, NULL); 101 finish_unlinks (ohci, ohci_frame_no(ohci), NULL); 102 ohci_writel (ohci, ohci_readl (ohci, &ohci->regs->intrstatus), 103 &ohci->regs->intrstatus); 104 105 /* maybe resume can wake root hub */ 106 if (hcd->remote_wakeup) 107 ohci->hc_control |= OHCI_CTRL_RWE; 108 else 109 ohci->hc_control &= ~OHCI_CTRL_RWE; 110 111 /* Suspend hub */ 112 ohci->hc_control &= ~OHCI_CTRL_HCFS; 113 ohci->hc_control |= OHCI_USB_SUSPEND; 114 ohci_writel (ohci, ohci->hc_control, &ohci->regs->control); 115 (void) ohci_readl (ohci, &ohci->regs->control); 116 117 /* no resumes until devices finish suspending */ 118 ohci->next_statechange = jiffies + msecs_to_jiffies (5); 119 120 done: 121 if (status == 0) 122 hcd->state = HC_STATE_SUSPENDED; 123 spin_unlock_irqrestore (&ohci->lock, flags); 124 return status; 125 } 126 127 static inline struct ed *find_head (struct ed *ed) 128 { 129 /* for bulk and control lists */ 130 while (ed->ed_prev) 131 ed = ed->ed_prev; 132 return ed; 133 } 134 135 /* caller has locked the root hub */ 136 static int ohci_hub_resume (struct usb_hcd *hcd) 137 { 138 struct ohci_hcd *ohci = hcd_to_ohci (hcd); 139 u32 temp, enables; 140 int status = -EINPROGRESS; 141 142 if (time_before (jiffies, ohci->next_statechange)) 143 msleep(5); 144 145 spin_lock_irq (&ohci->lock); 146 ohci->hc_control = ohci_readl (ohci, &ohci->regs->control); 147 148 if (ohci->hc_control & (OHCI_CTRL_IR | OHCI_SCHED_ENABLES)) { 149 /* this can happen after suspend-to-disk */ 150 if (hcd->state == HC_STATE_RESUMING) { 151 ohci_dbg (ohci, "BIOS/SMM active, control %03x\n", 152 ohci->hc_control); 153 status = -EBUSY; 154 /* this happens when pmcore resumes HC then root */ 155 } else { 156 ohci_dbg (ohci, "duplicate resume\n"); 157 status = 0; 158 } 159 } else switch (ohci->hc_control & OHCI_CTRL_HCFS) { 160 case OHCI_USB_SUSPEND: 161 ohci->hc_control &= ~(OHCI_CTRL_HCFS|OHCI_SCHED_ENABLES); 162 ohci->hc_control |= OHCI_USB_RESUME; 163 ohci_writel (ohci, ohci->hc_control, &ohci->regs->control); 164 (void) ohci_readl (ohci, &ohci->regs->control); 165 ohci_dbg (ohci, "resume root hub\n"); 166 break; 167 case OHCI_USB_RESUME: 168 /* HCFS changes sometime after INTR_RD */ 169 ohci_info (ohci, "wakeup\n"); 170 break; 171 case OHCI_USB_OPER: 172 ohci_dbg (ohci, "already resumed\n"); 173 status = 0; 174 break; 175 default: /* RESET, we lost power */ 176 ohci_dbg (ohci, "root hub hardware reset\n"); 177 status = -EBUSY; 178 } 179 spin_unlock_irq (&ohci->lock); 180 if (status == -EBUSY) { 181 (void) ohci_init (ohci); 182 return ohci_restart (ohci); 183 } 184 if (status != -EINPROGRESS) 185 return status; 186 187 temp = roothub_a (ohci) & RH_A_NDP; 188 enables = 0; 189 while (temp--) { 190 u32 stat = ohci_readl (ohci, 191 &ohci->regs->roothub.portstatus [temp]); 192 193 /* force global, not selective, resume */ 194 if (!(stat & RH_PS_PSS)) 195 continue; 196 ohci_writel (ohci, RH_PS_POCI, 197 &ohci->regs->roothub.portstatus [temp]); 198 } 199 200 /* Some controllers (lucent erratum) need extra-long delays */ 201 hcd->state = HC_STATE_RESUMING; 202 mdelay (20 /* usb 11.5.1.10 */ + 15); 203 204 temp = ohci_readl (ohci, &ohci->regs->control); 205 temp &= OHCI_CTRL_HCFS; 206 if (temp != OHCI_USB_RESUME) { 207 ohci_err (ohci, "controller won't resume\n"); 208 return -EBUSY; 209 } 210 211 /* disable old schedule state, reinit from scratch */ 212 ohci_writel (ohci, 0, &ohci->regs->ed_controlhead); 213 ohci_writel (ohci, 0, &ohci->regs->ed_controlcurrent); 214 ohci_writel (ohci, 0, &ohci->regs->ed_bulkhead); 215 ohci_writel (ohci, 0, &ohci->regs->ed_bulkcurrent); 216 ohci_writel (ohci, 0, &ohci->regs->ed_periodcurrent); 217 ohci_writel (ohci, (u32) ohci->hcca_dma, &ohci->regs->hcca); 218 219 /* Sometimes PCI D3 suspend trashes frame timings ... */ 220 periodic_reinit (ohci); 221 222 /* interrupts might have been disabled */ 223 ohci_writel (ohci, OHCI_INTR_INIT, &ohci->regs->intrenable); 224 if (ohci->ed_rm_list) 225 ohci_writel (ohci, OHCI_INTR_SF, &ohci->regs->intrenable); 226 ohci_writel (ohci, ohci_readl (ohci, &ohci->regs->intrstatus), 227 &ohci->regs->intrstatus); 228 229 /* Then re-enable operations */ 230 ohci_writel (ohci, OHCI_USB_OPER, &ohci->regs->control); 231 (void) ohci_readl (ohci, &ohci->regs->control); 232 msleep (3); 233 234 temp = OHCI_CONTROL_INIT | OHCI_USB_OPER; 235 if (hcd->can_wakeup) 236 temp |= OHCI_CTRL_RWC; 237 ohci->hc_control = temp; 238 ohci_writel (ohci, temp, &ohci->regs->control); 239 (void) ohci_readl (ohci, &ohci->regs->control); 240 241 /* TRSMRCY */ 242 msleep (10); 243 244 /* keep it alive for ~5x suspend + resume costs */ 245 ohci->next_statechange = jiffies + msecs_to_jiffies (250); 246 247 /* maybe turn schedules back on */ 248 enables = 0; 249 temp = 0; 250 if (!ohci->ed_rm_list) { 251 if (ohci->ed_controltail) { 252 ohci_writel (ohci, 253 find_head (ohci->ed_controltail)->dma, 254 &ohci->regs->ed_controlhead); 255 enables |= OHCI_CTRL_CLE; 256 temp |= OHCI_CLF; 257 } 258 if (ohci->ed_bulktail) { 259 ohci_writel (ohci, find_head (ohci->ed_bulktail)->dma, 260 &ohci->regs->ed_bulkhead); 261 enables |= OHCI_CTRL_BLE; 262 temp |= OHCI_BLF; 263 } 264 } 265 if (hcd->self.bandwidth_isoc_reqs || hcd->self.bandwidth_int_reqs) 266 enables |= OHCI_CTRL_PLE|OHCI_CTRL_IE; 267 if (enables) { 268 ohci_dbg (ohci, "restarting schedules ... %08x\n", enables); 269 ohci->hc_control |= enables; 270 ohci_writel (ohci, ohci->hc_control, &ohci->regs->control); 271 if (temp) 272 ohci_writel (ohci, temp, &ohci->regs->cmdstatus); 273 (void) ohci_readl (ohci, &ohci->regs->control); 274 } 275 276 hcd->state = HC_STATE_RUNNING; 277 return 0; 278 } 279 280 static void ohci_rh_resume (void *_hcd) 281 { 282 struct usb_hcd *hcd = _hcd; 283 284 usb_lock_device (hcd->self.root_hub); 285 (void) ohci_hub_resume (hcd); 286 usb_unlock_device (hcd->self.root_hub); 287 } 288 289 #else 290 291 static void ohci_rh_resume (void *_hcd) 292 { 293 struct ohci_hcd *ohci = hcd_to_ohci (_hcd); 294 ohci_dbg(ohci, "rh_resume ??\n"); 295 } 296 297 #endif /* CONFIG_USB_SUSPEND || CONFIG_PM */ 298 299 /*-------------------------------------------------------------------------*/ 300 301 /* build "status change" packet (one or two bytes) from HC registers */ 302 303 static int 304 ohci_hub_status_data (struct usb_hcd *hcd, char *buf) 305 { 306 struct ohci_hcd *ohci = hcd_to_ohci (hcd); 307 int ports, i, changed = 0, length = 1; 308 int can_suspend = hcd->can_wakeup; 309 unsigned long flags; 310 311 spin_lock_irqsave (&ohci->lock, flags); 312 313 /* handle autosuspended root: finish resuming before 314 * letting khubd or root hub timer see state changes. 315 */ 316 if ((ohci->hc_control & OHCI_CTRL_HCFS) != OHCI_USB_OPER 317 || !HC_IS_RUNNING(hcd->state)) { 318 can_suspend = 0; 319 goto done; 320 } 321 322 ports = roothub_a (ohci) & RH_A_NDP; 323 if (ports > MAX_ROOT_PORTS) { 324 ohci_err (ohci, "bogus NDP=%d, rereads as NDP=%d\n", ports, 325 ohci_readl (ohci, &ohci->regs->roothub.a) & RH_A_NDP); 326 /* retry later; "should not happen" */ 327 goto done; 328 } 329 330 /* init status */ 331 if (roothub_status (ohci) & (RH_HS_LPSC | RH_HS_OCIC)) 332 buf [0] = changed = 1; 333 else 334 buf [0] = 0; 335 if (ports > 7) { 336 buf [1] = 0; 337 length++; 338 } 339 340 /* look at each port */ 341 for (i = 0; i < ports; i++) { 342 u32 status = roothub_portstatus (ohci, i); 343 344 if (status & (RH_PS_CSC | RH_PS_PESC | RH_PS_PSSC 345 | RH_PS_OCIC | RH_PS_PRSC)) { 346 changed = 1; 347 if (i < 7) 348 buf [0] |= 1 << (i + 1); 349 else 350 buf [1] |= 1 << (i - 7); 351 continue; 352 } 353 354 /* can suspend if no ports are enabled; or if all all 355 * enabled ports are suspended AND remote wakeup is on. 356 */ 357 if (!(status & RH_PS_CCS)) 358 continue; 359 if ((status & RH_PS_PSS) && hcd->remote_wakeup) 360 continue; 361 can_suspend = 0; 362 } 363 done: 364 spin_unlock_irqrestore (&ohci->lock, flags); 365 366 #ifdef CONFIG_PM 367 /* save power by suspending idle root hubs; 368 * INTR_RD wakes us when there's work 369 * NOTE: if we can do this, we don't need a root hub timer! 370 */ 371 if (can_suspend 372 && !changed 373 && !ohci->ed_rm_list 374 && ((OHCI_CTRL_HCFS | OHCI_SCHED_ENABLES) 375 & ohci->hc_control) 376 == OHCI_USB_OPER 377 && time_after (jiffies, ohci->next_statechange) 378 && usb_trylock_device (hcd->self.root_hub) 379 ) { 380 ohci_vdbg (ohci, "autosuspend\n"); 381 (void) ohci_hub_suspend (hcd); 382 hcd->state = HC_STATE_RUNNING; 383 usb_unlock_device (hcd->self.root_hub); 384 } 385 #endif 386 387 return changed ? length : 0; 388 } 389 390 /*-------------------------------------------------------------------------*/ 391 392 static void 393 ohci_hub_descriptor ( 394 struct ohci_hcd *ohci, 395 struct usb_hub_descriptor *desc 396 ) { 397 u32 rh = roothub_a (ohci); 398 int ports = rh & RH_A_NDP; 399 u16 temp; 400 401 desc->bDescriptorType = 0x29; 402 desc->bPwrOn2PwrGood = (rh & RH_A_POTPGT) >> 24; 403 desc->bHubContrCurrent = 0; 404 405 desc->bNbrPorts = ports; 406 temp = 1 + (ports / 8); 407 desc->bDescLength = 7 + 2 * temp; 408 409 temp = 0; 410 if (rh & RH_A_NPS) /* no power switching? */ 411 temp |= 0x0002; 412 if (rh & RH_A_PSM) /* per-port power switching? */ 413 temp |= 0x0001; 414 if (rh & RH_A_NOCP) /* no overcurrent reporting? */ 415 temp |= 0x0010; 416 else if (rh & RH_A_OCPM) /* per-port overcurrent reporting? */ 417 temp |= 0x0008; 418 desc->wHubCharacteristics = (__force __u16)cpu_to_hc16(ohci, temp); 419 420 /* two bitmaps: ports removable, and usb 1.0 legacy PortPwrCtrlMask */ 421 rh = roothub_b (ohci); 422 desc->bitmap [0] = rh & RH_B_DR; 423 if (ports > 7) { 424 desc->bitmap [1] = (rh & RH_B_DR) >> 8; 425 desc->bitmap [2] = desc->bitmap [3] = 0xff; 426 } else 427 desc->bitmap [1] = 0xff; 428 } 429 430 /*-------------------------------------------------------------------------*/ 431 432 #ifdef CONFIG_USB_OTG 433 434 static int ohci_start_port_reset (struct usb_hcd *hcd, unsigned port) 435 { 436 struct ohci_hcd *ohci = hcd_to_ohci (hcd); 437 u32 status; 438 439 if (!port) 440 return -EINVAL; 441 port--; 442 443 /* start port reset before HNP protocol times out */ 444 status = ohci_readl(ohci, &ohci->regs->roothub.portstatus [port]); 445 if (!(status & RH_PS_CCS)) 446 return -ENODEV; 447 448 /* khubd will finish the reset later */ 449 ohci_writel(ohci, RH_PS_PRS, &ohci->regs->roothub.portstatus [port]); 450 return 0; 451 } 452 453 static void start_hnp(struct ohci_hcd *ohci); 454 455 #else 456 457 #define ohci_start_port_reset NULL 458 459 #endif 460 461 /*-------------------------------------------------------------------------*/ 462 463 464 /* See usb 7.1.7.5: root hubs must issue at least 50 msec reset signaling, 465 * not necessarily continuous ... to guard against resume signaling. 466 * The short timeout is safe for non-root hubs, and is backward-compatible 467 * with earlier Linux hosts. 468 */ 469 #ifdef CONFIG_USB_SUSPEND 470 #define PORT_RESET_MSEC 50 471 #else 472 #define PORT_RESET_MSEC 10 473 #endif 474 475 /* this timer value might be vendor-specific ... */ 476 #define PORT_RESET_HW_MSEC 10 477 478 /* wrap-aware logic morphed from <linux/jiffies.h> */ 479 #define tick_before(t1,t2) ((s16)(((s16)(t1))-((s16)(t2))) < 0) 480 481 /* called from some task, normally khubd */ 482 static inline void root_port_reset (struct ohci_hcd *ohci, unsigned port) 483 { 484 __hc32 __iomem *portstat = &ohci->regs->roothub.portstatus [port]; 485 u32 temp; 486 u16 now = ohci_readl(ohci, &ohci->regs->fmnumber); 487 u16 reset_done = now + PORT_RESET_MSEC; 488 489 /* build a "continuous enough" reset signal, with up to 490 * 3msec gap between pulses. scheduler HZ==100 must work; 491 * this might need to be deadline-scheduled. 492 */ 493 do { 494 /* spin until any current reset finishes */ 495 for (;;) { 496 temp = ohci_readl (ohci, portstat); 497 if (!(temp & RH_PS_PRS)) 498 break; 499 udelay (500); 500 } 501 502 if (!(temp & RH_PS_CCS)) 503 break; 504 if (temp & RH_PS_PRSC) 505 ohci_writel (ohci, RH_PS_PRSC, portstat); 506 507 /* start the next reset, sleep till it's probably done */ 508 ohci_writel (ohci, RH_PS_PRS, portstat); 509 msleep(PORT_RESET_HW_MSEC); 510 now = ohci_readl(ohci, &ohci->regs->fmnumber); 511 } while (tick_before(now, reset_done)); 512 /* caller synchronizes using PRSC */ 513 } 514 515 static int ohci_hub_control ( 516 struct usb_hcd *hcd, 517 u16 typeReq, 518 u16 wValue, 519 u16 wIndex, 520 char *buf, 521 u16 wLength 522 ) { 523 struct ohci_hcd *ohci = hcd_to_ohci (hcd); 524 int ports = hcd_to_bus (hcd)->root_hub->maxchild; 525 u32 temp; 526 int retval = 0; 527 528 switch (typeReq) { 529 case ClearHubFeature: 530 switch (wValue) { 531 case C_HUB_OVER_CURRENT: 532 ohci_writel (ohci, RH_HS_OCIC, 533 &ohci->regs->roothub.status); 534 case C_HUB_LOCAL_POWER: 535 break; 536 default: 537 goto error; 538 } 539 break; 540 case ClearPortFeature: 541 if (!wIndex || wIndex > ports) 542 goto error; 543 wIndex--; 544 545 switch (wValue) { 546 case USB_PORT_FEAT_ENABLE: 547 temp = RH_PS_CCS; 548 break; 549 case USB_PORT_FEAT_C_ENABLE: 550 temp = RH_PS_PESC; 551 break; 552 case USB_PORT_FEAT_SUSPEND: 553 temp = RH_PS_POCI; 554 if ((ohci->hc_control & OHCI_CTRL_HCFS) 555 != OHCI_USB_OPER) 556 schedule_work (&ohci->rh_resume); 557 break; 558 case USB_PORT_FEAT_C_SUSPEND: 559 temp = RH_PS_PSSC; 560 break; 561 case USB_PORT_FEAT_POWER: 562 temp = RH_PS_LSDA; 563 break; 564 case USB_PORT_FEAT_C_CONNECTION: 565 temp = RH_PS_CSC; 566 break; 567 case USB_PORT_FEAT_C_OVER_CURRENT: 568 temp = RH_PS_OCIC; 569 break; 570 case USB_PORT_FEAT_C_RESET: 571 temp = RH_PS_PRSC; 572 break; 573 default: 574 goto error; 575 } 576 ohci_writel (ohci, temp, 577 &ohci->regs->roothub.portstatus [wIndex]); 578 // ohci_readl (ohci, &ohci->regs->roothub.portstatus [wIndex]); 579 break; 580 case GetHubDescriptor: 581 ohci_hub_descriptor (ohci, (struct usb_hub_descriptor *) buf); 582 break; 583 case GetHubStatus: 584 temp = roothub_status (ohci) & ~(RH_HS_CRWE | RH_HS_DRWE); 585 *(__le32 *) buf = cpu_to_le32 (temp); 586 break; 587 case GetPortStatus: 588 if (!wIndex || wIndex > ports) 589 goto error; 590 wIndex--; 591 temp = roothub_portstatus (ohci, wIndex); 592 *(__le32 *) buf = cpu_to_le32 (temp); 593 594 #ifndef OHCI_VERBOSE_DEBUG 595 if (*(u16*)(buf+2)) /* only if wPortChange is interesting */ 596 #endif 597 dbg_port (ohci, "GetStatus", wIndex, temp); 598 break; 599 case SetHubFeature: 600 switch (wValue) { 601 case C_HUB_OVER_CURRENT: 602 // FIXME: this can be cleared, yes? 603 case C_HUB_LOCAL_POWER: 604 break; 605 default: 606 goto error; 607 } 608 break; 609 case SetPortFeature: 610 if (!wIndex || wIndex > ports) 611 goto error; 612 wIndex--; 613 switch (wValue) { 614 case USB_PORT_FEAT_SUSPEND: 615 #ifdef CONFIG_USB_OTG 616 if (hcd->self.otg_port == (wIndex + 1) 617 && hcd->self.b_hnp_enable) 618 start_hnp(ohci); 619 else 620 #endif 621 ohci_writel (ohci, RH_PS_PSS, 622 &ohci->regs->roothub.portstatus [wIndex]); 623 break; 624 case USB_PORT_FEAT_POWER: 625 ohci_writel (ohci, RH_PS_PPS, 626 &ohci->regs->roothub.portstatus [wIndex]); 627 break; 628 case USB_PORT_FEAT_RESET: 629 root_port_reset (ohci, wIndex); 630 break; 631 default: 632 goto error; 633 } 634 break; 635 636 default: 637 error: 638 /* "protocol stall" on error */ 639 retval = -EPIPE; 640 } 641 return retval; 642 } 643 644