[PATCH] mmc: part_switch: fixes switch on gp3 partition

[Dominique Martinet <asmadeus@codewreck.org>]

From: Dominique Martinet <dominique.martinet@atmark-techno.com>

Commit e7794c14fd73 ("mmc: rpmb: fixes pause retune on all RPMB
partitions.") added a mask check for 'part_type', but the mask used was
wrong leading to the code intended for rpmb also being executed for GP3.

On some MMCs (but not all) this would make gp3 partition inaccessible:
armadillo:~# head -c 1 < /dev/mmcblk2gp3
head: standard input: I/O error
armadillo:~# dmesg -c
[  422.976583] mmc2: running CQE recovery
[  423.058182] mmc2: running CQE recovery
[  423.137607] mmc2: running CQE recovery
[  423.137802] blk_update_request: I/O error, dev mmcblk2gp3, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 4 prio class 0
[  423.237125] mmc2: running CQE recovery
[  423.318206] mmc2: running CQE recovery
[  423.397680] mmc2: running CQE recovery
[  423.397837] blk_update_request: I/O error, dev mmcblk2gp3, sector 0 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[  423.408287] Buffer I/O error on dev mmcblk2gp3, logical block 0, async page read

the part_type values of interest here are defined as follow:
main  0
boot0 1
boot1 2
rpmb  3
gp0   4
gp1   5
gp2   6
gp3   7

so mask with EXT_CSD_PART_CONFIG_ACC_MASK (7) to correctly identify rpmb

Fixes: e7794c14fd73 ("mmc: rpmb: fixes pause retune on all RPMB partitions.")
Cc: stable@vger.kernel.org
Cc: Jorge Ramirez-Ortiz <jorge@foundries.io>
Signed-off-by: Dominique Martinet <dominique.martinet@atmark-techno.com>
---
A couple of notes:
- this doesn't fail on all eMMCs, I can still access gp3 on some models
  but it seems to fail reliably with micron's "G1M15L"
- I've encountered this on the 5.10 backport (in 5.10.208), so that'll
  need to be backported everywhere the fix was taken...

Thanks!
---
 drivers/mmc/core/block.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
index 32d49100dff5..86efa6084696 100644
--- a/drivers/mmc/core/block.c
+++ b/drivers/mmc/core/block.c
@@ -874,10 +874,11 @@ static const struct block_device_operations mmc_bdops = {
 static int mmc_blk_part_switch_pre(struct mmc_card *card,
 				   unsigned int part_type)
 {
-	const unsigned int mask = EXT_CSD_PART_CONFIG_ACC_RPMB;
+	const unsigned int mask = EXT_CSD_PART_CONFIG_ACC_MASK;
+	const unsigned int rpmb = EXT_CSD_PART_CONFIG_ACC_RPMB;
 	int ret = 0;
 
-	if ((part_type & mask) == mask) {
+	if ((part_type & mask) == rpmb) {
 		if (card->ext_csd.cmdq_en) {
 			ret = mmc_cmdq_disable(card);
 			if (ret)
@@ -892,10 +893,11 @@ static int mmc_blk_part_switch_pre(struct mmc_card *card,
 static int mmc_blk_part_switch_post(struct mmc_card *card,
 				    unsigned int part_type)
 {
-	const unsigned int mask = EXT_CSD_PART_CONFIG_ACC_RPMB;
+	const unsigned int mask = EXT_CSD_PART_CONFIG_ACC_MASK;
+	const unsigned int rpmb = EXT_CSD_PART_CONFIG_ACC_RPMB;
 	int ret = 0;
 
-	if ((part_type & mask) == mask) {
+	if ((part_type & mask) == rpmb) {
 		mmc_retune_unpause(card->host);
 		if (card->reenable_cmdq && !card->ext_csd.cmdq_en)
 			ret = mmc_cmdq_enable(card);

---
base-commit: 5847c9777c303a792202c609bd761dceb60f4eed
change-id: 20240306-mmc-partswitch-c3a50b5084ae

Best regards,
-- 
Dominique Martinet | Asmadeus