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| H A D | dw_mmc-rockchip.c | d4aa908c Thu May 12 13:31:50 CDT 2016 Douglas Anderson <dianders@chromium.org> mmc: dw_mmc: rockchip: Set the drive phase properly
Historically for Rockchip devices we've relied on the power-on
default (or perhaps the firmware setting) to get the correct drive
phase for dw_mmc devices. This worked OK for the most part, but:
* Relying on the setting just "being right" is a bit fragile.
* As soon as there is an instance where the power on default is wrong or
where the firmware didn't configure this properly then we'll get a
mysterious failure.
In commit 7a03fe6f48f3 ("clk: rockchip: reset init state before mmc card
initialization") we actually started setting this explicitly in the
kernel, but that commit wasn't quite right and also wasn't quite
enough. See <https://patchwork.kernel.org/patch/9085311/> for some
details.
Let's explicitly set this phase in dw_mmc.
The comments inside this patch try to explain the situation quite
throughly, but the high level overview of this is:
Before this patch on rk3288 devices tested (after revert of the clock
patch described above):
* eMMC: 180 degrees
* SDMMC/SDIO0/SDIO1: 90 degrees
After this patch:
* Use 90 degree phase offset usually.
* Use 180 degree phase offset for MMC_DDR52, SDR104, HS200.
That means we are _changing_ behavior for those devices in this way:
* If we have HS200 eMMC or DDR52 eMMC, we'll run ID mode at 90
degrees (vs 180) but otherwise have no change.
* For any non-HS200 / non-DDR52 eMMC devices we'll now _always_ run at
90 degrees (vs 180). It seems fairly unlikely that building modern
hardware is using an eMMC that isn't using DDR52 or HS200, of course.
* For SDR104 cards we'll now run with 180 degree phase offset (vs 90).
It's expected that 90 degree phase offset would have worked OK, but
this gives us extra margin.
I have tested this by inserting my collection of uSD cards (mostly UHS,
though a few not) into a veyron_minnie and confirmed that they still
seem to enumerate properly. For a subset of them I tried putting a
filesystem on them and also tried running mmc_test.
Fixes: 7a03fe6f48f3 ("clk: rockchip: reset init state before mmc card initialization")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Shawn Lin <shawn.lin@rock-chips.com>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
d4aa908c Thu May 12 13:31:50 CDT 2016 Douglas Anderson <dianders@chromium.org> mmc: dw_mmc: rockchip: Set the drive phase properly
Historically for Rockchip devices we've relied on the power-on
default (or perhaps the firmware setting) to get the correct drive
phase for dw_mmc devices. This worked OK for the most part, but:
* Relying on the setting just "being right" is a bit fragile.
* As soon as there is an instance where the power on default is wrong or
where the firmware didn't configure this properly then we'll get a
mysterious failure.
In commit 7a03fe6f48f3 ("clk: rockchip: reset init state before mmc card
initialization") we actually started setting this explicitly in the
kernel, but that commit wasn't quite right and also wasn't quite
enough. See <https://patchwork.kernel.org/patch/9085311/> for some
details.
Let's explicitly set this phase in dw_mmc.
The comments inside this patch try to explain the situation quite
throughly, but the high level overview of this is:
Before this patch on rk3288 devices tested (after revert of the clock
patch described above):
* eMMC: 180 degrees
* SDMMC/SDIO0/SDIO1: 90 degrees
After this patch:
* Use 90 degree phase offset usually.
* Use 180 degree phase offset for MMC_DDR52, SDR104, HS200.
That means we are _changing_ behavior for those devices in this way:
* If we have HS200 eMMC or DDR52 eMMC, we'll run ID mode at 90
degrees (vs 180) but otherwise have no change.
* For any non-HS200 / non-DDR52 eMMC devices we'll now _always_ run at
90 degrees (vs 180). It seems fairly unlikely that building modern
hardware is using an eMMC that isn't using DDR52 or HS200, of course.
* For SDR104 cards we'll now run with 180 degree phase offset (vs 90).
It's expected that 90 degree phase offset would have worked OK, but
this gives us extra margin.
I have tested this by inserting my collection of uSD cards (mostly UHS,
though a few not) into a veyron_minnie and confirmed that they still
seem to enumerate properly. For a subset of them I tried putting a
filesystem on them and also tried running mmc_test.
Fixes: 7a03fe6f48f3 ("clk: rockchip: reset init state before mmc card initialization")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Shawn Lin <shawn.lin@rock-chips.com>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
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