6.17-stable review patch. If anyone has any objections, please let me know.
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From: Rex Chen rex.chen_1@nxp.com
commit fef12d9f5bcf7e2b19a7cf1295c6abd5642dd241 upstream.
For multiple block read, the current implementation, transfer packet includes cmd53 + cmd53 response + block nums*(1byte token + block length bytes payload + 2bytes CRC + 1byte transfer), the last 1byte transfer of every block is not needed, so remove it.
Why doesn't multiple block read need CRC ack? For read operation, host side get the payload and CRC value, then will only check the CRC value to confirm if the data is correct or not, but not send CRC ack to card. If the data is correct, save it, or discard it and retransmit if data is error, so the last 1byte transfer of every block make no sense.
What's the side effect of this 1byte transfer? As the SPI is full duplex, if add this redundant 1byte transfer, SDIO card side take it as the token of next block, then all the next sub blocks sequence distort.
Signed-off-by: Rex Chen rex.chen_1@nxp.com Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20250728082230.1037917-3-rex.chen_1@nxp.com Signed-off-by: Ulf Hansson ulf.hansson@linaro.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/mmc/host/mmc_spi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/mmc/host/mmc_spi.c +++ b/drivers/mmc/host/mmc_spi.c @@ -563,7 +563,7 @@ mmc_spi_setup_data_message(struct mmc_sp * the next token (next data block, or STOP_TRAN). We can try to * minimize I/O ops by using a single read to collect end-of-busy. */ - if (multiple || write) { + if (write) { t = &host->early_status; memset(t, 0, sizeof(*t)); t->len = write ? sizeof(scratch->status) : 1;