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SubjectRe: [PATCH] mmc: dw_mmc: Don't send clock off command if power is off
Hi Doug,

On Fri, Mar 20, 2015 at 11:30 PM, Doug Anderson <dianders@chromium.org> wrote:
> We've already seen that it causes failures if we try to send the
> "SDMMC_CMD_UPD_CLK" command when power is off to the system. Here's
> another case where we were doing it: we were sending an
> SDMMC_CMD_UPD_CLK to set the clock to 0 when the card was already
> powered off and the clock was already at 0. Let's avoid that command
> and avoid problems.
>
> Signed-off-by: Doug Anderson <dianders@chromium.org>
> ---
> drivers/mmc/host/dw_mmc.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> index 47dfd0e..aeec698 100644
> --- a/drivers/mmc/host/dw_mmc.c
> +++ b/drivers/mmc/host/dw_mmc.c
> @@ -1172,8 +1172,9 @@ static void dw_mci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
>
> break;
> case MMC_POWER_OFF:
> - /* Turn clock off before power goes down */
> - dw_mci_setup_bus(slot, false);
> + /* Turn clock off before power goes down; only if powered */
> + if (slot->host->vqmmc_enabled)
> + dw_mci_setup_bus(slot, false);
>
vqmmc_enabled is always _true_ when entering MMC_POWER_OFF case..right?
Is this done for extra protection? Or do you have a case where vqmmc
is OFF and driver still calls dw_mci_setup_bus from here?

> if (!IS_ERR(mmc->supply.vmmc))
> mmc_regulator_set_ocr(mmc, mmc->supply.vmmc, 0);
> --
> 2.2.0.rc0.207.ga3a616c
>
> --
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--
Regards,
Alim


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