This is a note to let you know that I've just added the patch titled
mmc: core: properly select voltage range without power cycle
to the 5.4-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-core-properly-select-voltage-range-without-power-cycle.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 39a72dbfe188291b156dd6523511e3d5761ce775 Mon Sep 17 00:00:00 2001
From: Yann Gautier <yann.gautier@xxxxxxxxxxx>
Date: Fri, 28 Oct 2022 09:37:40 +0200
Subject: mmc: core: properly select voltage range without power cycle
From: Yann Gautier <yann.gautier@xxxxxxxxxxx>
commit 39a72dbfe188291b156dd6523511e3d5761ce775 upstream.
In mmc_select_voltage(), if there is no full power cycle, the voltage
range selected at the end of the function will be on a single range
(e.g. 3.3V/3.4V). To keep a range around the selected voltage (3.2V/3.4V),
the mask shift should be reduced by 1.
This issue was triggered by using a specific SD-card (Verbatim Premium
16GB UHS-1) on an STM32MP157C-DK2 board. This board cannot do UHS modes
and there is no power cycle. And the card was failing to switch to
high-speed mode. When adding the range 3.2V/3.3V for this card with the
proposed shift change, the card can switch to high-speed mode.
Fixes: ce69d37b7d8f ("mmc: core: Prevent violation of specs while initializing cards")
Signed-off-by: Yann Gautier <yann.gautier@xxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/20221028073740.7259-1-yann.gautier@xxxxxxxxxxx
Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/mmc/core/core.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -1145,7 +1145,13 @@ u32 mmc_select_voltage(struct mmc_host *
mmc_power_cycle(host, ocr);
} else {
bit = fls(ocr) - 1;
- ocr &= 3 << bit;
+ /*
+ * The bit variable represents the highest voltage bit set in
+ * the OCR register.
+ * To keep a range of 2 values (e.g. 3.2V/3.3V and 3.3V/3.4V),
+ * we must shift the mask '3' with (bit - 1).
+ */
+ ocr &= 3 << (bit - 1);
if (bit != host->ios.vdd)
dev_warn(mmc_dev(host), "exceeding card's volts\n");
}
Patches currently in stable-queue which might be from yann.gautier@xxxxxxxxxxx are
queue-5.4/mmc-core-properly-select-voltage-range-without-power-cycle.patch
