mach-snapdragon: capsule_update: Fix eMMC detection for non-UFS devices

Currently (since 2026.01-rc) on all SDM630/660 based devices this is
printed, after observing long boot delay (several seconds) before
executing preboot commands:

 QCOM-FMP: Failed to find boot partition

find_target_partition() function incorrectly assumes that eMMC is always
at number 0. In general you can't rely on device numbering to determine if
particular block device is eMMC or SD-card, because it depends on how
aliases are defined in device tree "chosen" node. Some SoCs have MMC
numbers starting at 1, not 0; so mmc1 is eMMC, mmc2 is SD-card.

Make eMMC detection reliable by using IS_SD() macro from mmc.h header.
Using this method target boot partition can be found successfully.
With debug prints enabled, this is printed:

 QCOM-FMP: skipped SD-Card (devnum 2)
 QCOM-FMP: Capsule update target: boot (disk 1:60)
 QCOM-FMP: DFU string: 'mmc 0=u-boot.bin part 1 60'

Without debug prints nothing is printed, no error about failure to find
boot partition.

Fixes: fe80a5f80095 ("mach-snapdragon: CapsuleUpdate: support all boot methods")
Signed-off-by: Alexey Minnekhanov <[email protected]>
Reviewed-by: Casey Connolly <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Casey Connolly <[email protected]>

1 files changed, 24 insertions, 4 deletions

diff --git a/arch/arm/mach-snapdragon/capsule_update.c b/arch/arm/mach-snapdragon/capsule_update.c
index 3699d91852d..586682434b7 100644
--- a/arch/arm/mach-snapdragon/capsule_update.c
+++ b/arch/arm/mach-snapdragon/capsule_update.c
@@ -13,6 +13,7 @@
 #include <efi.h>
 #include <efi_loader.h>
 #include <malloc.h>
+#include <mmc.h>
 #include <scsi.h>
 #include <part.h>
 #include <linux/err.h>
@@ -80,6 +81,23 @@ static enum ab_slot get_part_slot(const char *partname)
 	return SLOT_NONE;
 }
 
+/* Shamelessly copied from lib/efi_loader/efi_device_path.c @ 33 */
+/*
+ * Determine if an MMC device is an SD card.
+ *
+ * @desc	block device descriptor
+ * Return:	true if the device is an SD card
+ */
+static bool is_sd(struct blk_desc *desc)
+{
+	struct mmc *mmc = find_mmc_device(desc->devnum);
+
+	if (!mmc)
+		return false;
+
+	return IS_SD(mmc) != 0U;
+}
+
 /*
  * Determine which partition U-Boot is flashed to based on the boot source (ABL/XBL),
  * the slot status, and prioritizing the uefi partition over xbl if found.
@@ -109,19 +127,21 @@ static int find_target_partition(int *devnum, enum uclass_id *uclass,
 		if (device_get_uclass_id(dev) != UCLASS_BLK)
 			continue;
 
+		desc = dev_get_uclass_plat(dev);
+
 		/* If we have a UFS then don't look at any other block devices */
 		if (have_ufs) {
 			if (device_get_uclass_id(dev->parent->parent) != UCLASS_UFS)
 				continue;
+		}
 		/*
-		 * If we don't have UFS, then U-Boot must be on the eMMC which is always the first
-		 * MMC device.
+		 * If we don't have UFS, then U-Boot must be on the eMMC
 		 */
-		} else if (dev->parent->seq_ > 0) {
+		else if (IS_ENABLED(CONFIG_MMC) && is_sd(desc)) {
+			log_debug("skipped SD-Card (devnum %d)\n", desc->devnum);
 			continue;
 		}
 
-		desc = dev_get_uclass_plat(dev);
 		if (!desc || desc->part_type == PART_TYPE_UNKNOWN)
 			continue;
 		for (partnum = 1;; partnum++) {