Re: [PATCH v42 08/98] hw/sd/sdcard: Send NUM_WR_BLOCKS bits MSB first (ACMD22)

[Peter Maydell]

On Fri, 28 Jun 2024 at 08:05, Philippe Mathieu-Daudé <philmd@linaro.org> wrote:
>
> Per sections 3.6.1 (SD Bus Protocol), 4.3.4 "Data Write"
> and 7.3.2 (Responses):
>
>   In the CMD line the Most Significant Bit is transmitted first.
>
> Use the stl_be_p() helper to store the value in big-endian.
>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> Tested-by: Cédric Le Goater <clg@redhat.com>
> ---
> RFC because I'm surprised this has been unnoticed for 17 years
> (commit a1bb27b1e9 "initial SD card emulation", April 2007).
>
> Cc: Peter Maydell <peter.maydell@linaro.org>
> ---
>  hw/sd/sd.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)

I think Linux only uses this command in an error-recovery
code path (which we should never get into since our
emulated SD card has 100% reliability ;-)), which is
probably why we haven't noticed this before.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

thanks
-- PMM