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Re: [Qemu-devel] [PATCH arm-devs v1 1/5] sd/sd.c: Fix "inquiry" ACMD41
From: |
Peter Crosthwaite |
Subject: |
Re: [Qemu-devel] [PATCH arm-devs v1 1/5] sd/sd.c: Fix "inquiry" ACMD41 |
Date: |
Thu, 23 May 2013 09:42:02 +1000 |
Hi Igor,
On Wed, May 22, 2013 at 11:37 PM, Igor Mitsyanko <address@hidden> wrote:
>
> On 05/21/2013 10:50 AM, address@hidden wrote:
>
> From: Peter Crosthwaite <address@hidden>
>
> the SD command ACMD41 can be used in a read only mode to query device
> state without doing the SD card initialisation. This is valid even
> which the device is already initialised. Fix the command to be
> responsive when in the ready state accordingly.
>
> Signed-off-by: Peter Crosthwaite <address@hidden>
> ---
>
> hw/sd/sd.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/hw/sd/sd.c b/hw/sd/sd.c
> index 2e0ef3e..89bfb7a 100644
> --- a/hw/sd/sd.c
> +++ b/hw/sd/sd.c
> @@ -1277,6 +1277,7 @@ static sd_rsp_type_t sd_app_command(SDState *sd,
> }
> switch (sd->state) {
> case sd_idle_state:
> + case sd_ready_state:
> /* We accept any voltage. 10000 V is nothing. */
> if (req.arg)
> sd->state = sd_ready_state;
>
>
> I couldn't find any info in SD specification that would confirm this change
> correctness, what about
> table "Table 4-29: Card State Transition Table" which states that ACMD41 is
> illegal in "ready" state?
>
By the letter of the spec I think you are right. Although this patch
is needed to make my QEMU consistent with my real hardware. I'll dig
deeper.
Regards,
Peter
> --
> Best wishes,
> Igor Mitsyanko
> email: address@hidden