[PATCH v2] mmc: Remove alignment hole for cmdidx in struct mmc_cmd

[Jonas Karlman]

The alignment hole caused by cmdidx in struct mmc_cmd cause strange
issues together with the peephole2 optimization on Amlogic SoCs.
Following was observed while working on SPL support for Amlogic SoCs.

sd_get_capabilities() normally issue a CMD55 followed by a CMD51.
However, on at least Amlogic S905 (Cortex-A53) and S905X3 (Cortex-A55),
CMD55 was instead followed by CMD8 (and a few reties) in SPL.

Code from the call site:

  cmd.cmdidx = SD_CMD_APP_SEND_SCR; // 51
  ...
  data.blocksize = 8;
  ...
  err = mmc_send_cmd_retry(mmc, &cmd, &data, 3);

Running the code with MMC_TRACE enabled shows:

CMD_SEND:55
                ARG                      0x50480000
                MMC_RSP_R1,5,6,7         0x00000920
CMD_SEND:8
                ARG                      0x00000000
                RET                      -110

Removing the alignment hole by changing cmdidx from ushort to uint or
building with -fno-peephole2 flag seem to resolve this issue.

CMD_SEND:55
                ARG                      0x50480000
                MMC_RSP_R1,5,6,7         0x00000920
CMD_SEND:51
                ARG                      0x00000000
                MMC_RSP_R1,5,6,7         0x00000920

Same issue was observed building U-Boot with gcc 8 - 13.

Remove this alignment hole by changing cmdidx from ushort to uint.

Signed-off-by: Jonas Karlman <jonas at kwiboo.se>
---
Changes in v2:
- Drop use of -fno-peephole2 flag

Link to RFC: https://patchwork.ozlabs.org/patch/1841495/
---
 include/mmc.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/mmc.h b/include/mmc.h
index 1022db3ffa7c..031ea0fb3545 100644
--- a/include/mmc.h
+++ b/include/mmc.h
@@ -413,7 +413,7 @@ struct mmc_cid {
 };
 
 struct mmc_cmd {
-	ushort cmdidx;
+	uint cmdidx;
 	uint resp_type;
 	uint cmdarg;
 	uint response[4];
-- 
2.43.0