This is a note to let you know that I've just added the patch titled mmc: sdhci-pci: Fix eMMC driver strength for BYT-based controllers to the 5.6-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: mmc-sdhci-pci-fix-emmc-driver-strength-for-byt-based.patch and it can be found in the queue-5.6 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit bd144497dc180c3cfdb05700206126581836e009 Author: Adrian Hunter <adrian.hunter@xxxxxxxxx> Date: Wed Apr 22 14:16:29 2020 +0300 mmc: sdhci-pci: Fix eMMC driver strength for BYT-based controllers commit 1a8eb6b373c2af6533c13d1ea11f504e5010ed9a upstream. 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@xxxxxxxxx> Fixes: 51ced59cc02e ("mmc: sdhci-pci: Use ACPI DSM to get driver strength for some Intel devices") Cc: stable@xxxxxxxxxxxxxxx Link: https://lore.kernel.org/r/20200422111629.4899-1-adrian.hunter@xxxxxxxxx Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> diff --git a/drivers/mmc/host/sdhci-pci-core.c b/drivers/mmc/host/sdhci-pci-core.c index 525de2454a4de..2527244c2ae16 100644 --- a/drivers/mmc/host/sdhci-pci-core.c +++ b/drivers/mmc/host/sdhci-pci-core.c @@ -601,6 +601,9 @@ static int intel_select_drive_strength(struct mmc_card *card, struct sdhci_pci_slot *slot = sdhci_priv(host); struct intel_host *intel_host = sdhci_pci_priv(slot); + if (!(mmc_driver_type_mask(intel_host->drv_strength) & card_drv)) + return 0; + return intel_host->drv_strength; }