tag ad2edba2d130070c0477388281419993b6b3a074
tagger Ulf Hansson <ulf.hansson@linaro.org> Thu Apr 30 08:49:28 2020 +0200
object 1a8eb6b373c2af6533c13d1ea11f504e5010ed9a

MMC host:
 - meson-mx-sdio: Fix support for HW busy detection
 - sdhci-msm: Fix support for HW busy detection
 - cqhci: Fix polling loop by converting to readx_poll_timeout()
 - sdhci-xenon: Fix annoying 1.8V regulator warning
 - sdhci-pci: Fix eMMC driver strength for BYT-based controllers

commit 1a8eb6b373c2af6533c13d1ea11f504e5010ed9a
author Adrian Hunter <adrian.hunter@intel.com> Wed Apr 22 14:16:29 2020 +0300
committer Ulf Hansson <ulf.hansson@linaro.org> Wed Apr 22 17:57:17 2020 +0200
tree 01e0de0bcd7743bb94b111522b015cf1bc1b39aa
parent bb32e1987bc55ce1db400faf47d85891da3c9b9f

mmc: sdhci-pci: Fix eMMC driver strength for BYT-based controllers

BIOS writers have begun the practice of setting 40 ohm eMMC driver strength
even though the eMMC may not support it, on the assumption that the kernel
will validate the value against the eMMC (Extended CSD DRIVER_STRENGTH
[offset 197]) and revert to the default 50 ohm value if 40 ohm is invalid.

This is done to avoid changing the value for different boards.

Putting aside the merits of this approach, it is clear the eMMC's mask
of supported driver strengths is more reliable than the value provided
by BIOS. Add validation accordingly.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Fixes: 51ced59cc02e ("mmc: sdhci-pci: Use ACPI DSM to get driver strength for some Intel devices")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20200422111629.4899-1-adrian.hunter@intel.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>