Hi Michal,
The patch itself looks good, but there's a few style issues.
On Sun, May 24, 2015 at 08:07:32PM +0200, Michal Suchanek wrote:
> The 250ms timeout is too short.
>
> On my system enabling the oclk takes under 50ms and disabling slightly
> over 100ms when idle. Under load disabling the clock can take over
> 350ms.
>
> This does not make mmc clock gating look like good option to have on
> sunxi but the system should not crash with mmc clock gating enabled
> nonetheless.
>
> This patch sets the timeout to 750ms and adds debug prints which show
> how long enabling/disabling the clock took so more data can be collected
> from other systems.
>
> Signed-off-by: Michal Suchanek <hramrach@xxxxxxxxx>
> ---
> drivers/mmc/host/sunxi-mmc.c | 22 +++++++++++++++++++---
> 1 file changed, 19 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/mmc/host/sunxi-mmc.c b/drivers/mmc/host/sunxi-mmc.c
> index 4d3e1ff..7cdeecd 100644
> --- a/drivers/mmc/host/sunxi-mmc.c
> +++ b/drivers/mmc/host/sunxi-mmc.c
> @@ -595,7 +595,7 @@ static irqreturn_t sunxi_mmc_handle_manual_stop(int irq, void *dev_id)
>
> static int sunxi_mmc_oclk_onoff(struct sunxi_mmc_host *host, u32 oclk_en)
> {
> - unsigned long expire = jiffies + msecs_to_jiffies(250);
> + unsigned long start, end;
> u32 rval;
>
> rval = mmc_readl(host, REG_CLKCR);
> @@ -604,6 +604,8 @@ static int sunxi_mmc_oclk_onoff(struct sunxi_mmc_host *host, u32 oclk_en)
> if (oclk_en)
> rval |= SDXC_CARD_CLOCK_ON;
>
> + start = jiffies;
> + end = start + msecs_to_jiffies(750);
> mmc_writel(host, REG_CLKCR, rval);
>
> rval = SDXC_START | SDXC_UPCLK_ONLY | SDXC_WAIT_PRE_OVER;
> @@ -611,15 +613,29 @@ static int sunxi_mmc_oclk_onoff(struct sunxi_mmc_host *host, u32 oclk_en)
>
> do {
> rval = mmc_readl(host, REG_CMDR);
> - } while (time_before(jiffies, expire) && (rval & SDXC_START));
> + } while (time_before(jiffies, end) && (rval & SDXC_START));
> + end = jiffies;
>
> /* clear irq status bits set by the command */
> mmc_writel(host, REG_RINTR,
> mmc_readl(host, REG_RINTR) & ~SDXC_SDIO_INTERRUPT);
>
> if (rval & SDXC_START) {
> - dev_err(mmc_dev(host->mmc), "fatal err update clk timeout\n");
> + dev_err(mmc_dev(host->mmc),
> + "fatal err update oclk timeout. Could not %s in %ims.\n",
> + oclk_en ? "enable" : "disable",
> + jiffies_to_msecs(end-start));
You should have spaces around that operator.
> return -EIO;
> + } else {
> + int msecs = jiffies_to_msecs(end-start);
Ditto.
> + const char *ing = oclk_en ? "enabling" : "disabling";
> +
> + if ((msecs > 150) || (oclk_en && (msecs > 50)))
> + dev_warn(mmc_dev(host->mmc),
> + "%s oclk took %ims", ing, msecs);
> + else
> + dev_dbg(mmc_dev(host->mmc),
> + "%s oclk took %ims", ing, msecs);
And this should be aligned with the opening parenthesis.
Thanks!
Maxime
--
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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