Re: [Qemu-devel] [PATCH 1/3] sd: sdhci: Delete over-zealous power check

[Peter Crosthwaite <crosthwaitepeter@gmail.com>]

On Wed, Dec 16, 2015 at 11:47 AM, Andrew Baumann
<Andrew.Baumann@microsoft.com> wrote:
> This check was conditionalising SD card operation on the card being
> powered by the SDHCI host controller. It is however possible
> (particularly in embedded systems) for the power control of the SD card
> to be managed outside of SDHCI. This can be as trivial as hard-wiring
> the SD slot VCC to a constant power-rail.
>
> This means the guest SDHCI can validly opt-out of the SDHCI power
> control feature while still using the card. So delete this check to
> allow operation of the card with SDHCI power control.
>
> This is needed for at least Xilinx Zynq and also makes Freescale i.MX25
> work for me. The digilent Zybo board has a public schematic
> which shows SD VCC hardwiring:
>

You should add a note that it is needed for rPI as well.

> http://digilentinc.com/Data/Products/ZYBO/ZYBO_sch_VB.3.pdf
> bottom of page 3.
>
> Signed-off-by: Peter Crosthwaite <crosthwaite.peter@gmail.com>
> Reviewed-by: Sai Pavan Boddu <sai.pavan.boddu@xilinx.com>

You should add your tested-by as it is valuable as non-author. Pavan
probably should be CC'd singly (got can be configured to do this
automatically) but I would just CC him whole series as he has does
some SD work.

At this point here you add committable notes about what you have
changed since the original authorship. If you added the note about
fixing rPI, something like:

[ AB changes:
 * Add rPI to list of devices fixed in commit message
]

> Signed-off-by: Andrew Baumann <Andrew.Baumann@microsoft.com>
> ---
>
> Notes:
>     This is exactly equivalent to Peter's patch here:
>     https://lists.gnu.org/archive/html/qemu-devel/2015-11/msg06271.html
>     ... which is why I've copied the signed-off-by lines (I assume that is
>     legit; if not, my apologies!). It is also needed for Pi.
>

The correct process it to apply the patch locally as originally,
authored then append your SoB and any notes/changes using git commit
--amend. Git am can apply the patch from an mbox, or the patches
utility can be used to download and apply patches off the list. You
could in this instance grab the original patch from my github tree:

https://github.com/pcrost/qemu/commit/db8e44ad1d31418fb4b5aaacc8552a39bb2d670f

Regards,
Peter

>  hw/sd/sdhci.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/hw/sd/sdhci.c b/hw/sd/sdhci.c
> index 8612760..bc39d48 100644
> --- a/hw/sd/sdhci.c
> +++ b/hw/sd/sdhci.c
> @@ -831,7 +831,7 @@ static void sdhci_data_transfer(void *opaque)
>
>  static bool sdhci_can_issue_command(SDHCIState *s)
>  {
> -    if (!SDHC_CLOCK_IS_ON(s->clkcon) || !(s->pwrcon & SDHC_POWER_ON) ||
> +    if (!SDHC_CLOCK_IS_ON(s->clkcon) ||
>          (((s->prnsts & SDHC_DATA_INHIBIT) || s->stopped_state) &&
>          ((s->cmdreg & SDHC_CMD_DATA_PRESENT) ||
>          ((s->cmdreg & SDHC_CMD_RESPONSE) == SDHC_CMD_RSP_WITH_BUSY &&
> --
> 2.5.3
>