[PATCH] mmc: dw_mmc: Turn the card clock off at suspend time
abrestic at chromium.org
Wed Nov 19 11:03:43 PST 2014
On Wed, Nov 19, 2014 at 10:51 AM, Doug Anderson <dianders at chromium.org> wrote:
> Since the dw_mmc driver was first added to Linux it's had a TODO in it
> that we should turn off the card clock during suspend. I have no idea
> for sure why it wasn't done originally, but if I had to guess I'd
> guess it was related to the lack of a common clock framework. Let's
> do it now.
> There is no reason for the card clock to be left on during suspend and
> most systems will eventually turn it off anyway (when whole clock
> trees are disabled). However, it's good to be explicit that it's
> disabled at the time that the MMC subsystem is disabled.
Should the bus clock (biu) be disabled as well?
> This actually fixes a bug on Rockchip rk3288 where an SDIO card wakes
> the system back up during suspend.
> Signed-off-by: Doug Anderson <dianders at chromium.org>
> drivers/mmc/host/dw_mmc.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> index 5a37c33..c448159 100644
> --- a/drivers/mmc/host/dw_mmc.c
> +++ b/drivers/mmc/host/dw_mmc.c
> @@ -2825,11 +2825,10 @@ EXPORT_SYMBOL(dw_mci_remove);
> #ifdef CONFIG_PM_SLEEP
> - * TODO: we should probably disable the clock to the card in the suspend path.
> - */
> int dw_mci_suspend(struct dw_mci *host)
> + clk_disable(host->ciu_clk);
I think you need to check for IS_ERR(host->ciu_clk) since the clock is
optional. Also, maybe disable_unprepare instead of just disable?
> @@ -2838,6 +2837,8 @@ int dw_mci_resume(struct dw_mci *host)
> int i, ret;
> + clk_enable(host->ciu_clk);
Check return value?
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