4bc31edebd
Way back in commit 4f25580fb84d ("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:
08573eaf1a70 ("mmc: mmc: do not use CMD13 to get status after speed mode
switch")
53e60650f74e ("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: 08573eaf1a70 ("mmc: mmc: do not use CMD13 to get status after speed mode switch")
Fixes: 53e60650f74e ("mmc: core: Allow CMD13 polling when switching to HS mode for mmc")
Fixes: 4f25580fb84d ("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>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.