]> git.baikalelectronics.ru Git - kernel.git/commit
mmc: core: Set HS clock speed before sending HS CMD13
authorBrian Norris <briannorris@chromium.org>
Fri, 22 Apr 2022 17:08:53 +0000 (10:08 -0700)
committerUlf Hansson <ulf.hansson@linaro.org>
Tue, 26 Apr 2022 11:55:50 +0000 (13:55 +0200)
commitfd8c4446e83526eaf8a51c8419be5a1b776bfc55
tree29074823260223ad531c9b7bb564cbf98534492e
parent7c464de09a7344a2cfcff7733684bbcf4ce79cc5
mmc: core: Set HS clock speed before sending HS CMD13

Way back in commit d68adef624bd ("mmc: core: changes frequency to
hs_max_dtr when selecting hs400es"), Rockchip engineers noticed that
some eMMC don't respond to SEND_STATUS commands very reliably if they're
still running at a low initial frequency. As mentioned in that commit,
JESD84-B51 P49 suggests a sequence in which the host:
1. sets HS_TIMING
2. bumps the clock ("<= 52 MHz")
3. sends further commands

It doesn't exactly require that we don't use a lower-than-52MHz
frequency, but in practice, these eMMC don't like it.

The aforementioned commit tried to get that right for HS400ES, although
it's unclear whether this ever truly worked as committed into mainline,
as other changes/refactoring adjusted the sequence in conflicting ways:

2ffe91b8f795 ("mmc: mmc: do not use CMD13 to get status after speed mode
switch")

923b9785f469 ("mmc: core: Allow CMD13 polling when switching to HS mode
for mmc")

In any case, today we do step 3 before step 2. Let's fix that, and also
apply the same logic to HS200/400, where this eMMC has problems too.

Resolves errors like this seen when booting some RK3399 Gru/Scarlet
systems:

[    2.058881] mmc1: CQHCI version 5.10
[    2.097545] mmc1: SDHCI controller on fe330000.mmc [fe330000.mmc] using ADMA
[    2.209804] mmc1: mmc_select_hs400es failed, error -84
[    2.215597] mmc1: error -84 whilst initialising MMC card
[    2.417514] mmc1: mmc_select_hs400es failed, error -110
[    2.423373] mmc1: error -110 whilst initialising MMC card
[    2.605052] mmc1: mmc_select_hs400es failed, error -110
[    2.617944] mmc1: error -110 whilst initialising MMC card
[    2.835884] mmc1: mmc_select_hs400es failed, error -110
[    2.841751] mmc1: error -110 whilst initialising MMC card

Ealier versions of this patch bumped to 200MHz/HS200 speeds too early,
which caused issues on, e.g., qcom-msm8974-fairphone-fp2. (Thanks for
the report Luca!) After a second look, it appears that aligns with
JESD84 / page 45 / table 28, so we need to keep to lower (HS / 52 MHz)
rates first.

Fixes: 2ffe91b8f795 ("mmc: mmc: do not use CMD13 to get status after speed mode switch")
Fixes: 923b9785f469 ("mmc: core: Allow CMD13 polling when switching to HS mode for mmc")
Fixes: d68adef624bd ("mmc: core: changes frequency to hs_max_dtr when selecting hs400es")
Cc: Shawn Lin <shawn.lin@rock-chips.com>
Link: https://lore.kernel.org/linux-mmc/11962455.O9o76ZdvQC@g550jk/
Reported-by: Luca Weiss <luca@z3ntu.xyz>
Signed-off-by: Brian Norris <briannorris@chromium.org>
Tested-by: Luca Weiss <luca@z3ntu.xyz>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20220422100824.v4.1.I484f4ee35609f78b932bd50feed639c29e64997e@changeid
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
drivers/mmc/core/mmc.c