[PATCH v4 2/4] mmc: dw_mmc: Add exynos resume_noirq callback to clear WAKEUP_INT
dianders at chromium.org
Fri Aug 9 11:05:43 EDT 2013
On Fri, Aug 9, 2013 at 6:33 AM, Seungwon Jeon <tgih.jun at samsung.com> wrote:
> On Wed, August 07, 2013, Doug Anderson wrote:
>> If the WAKEUP_INT is asserted at wakeup and not cleared, we'll end up
>> looping around forever. This has been seen to happen on exynos5420
>> silicon despite the fact that we haven't enabled any wakeup events due
>> to a silicon errata. It is safe to do on all exynos variants.
>> Signed-off-by: Doug Anderson <dianders at chromium.org>
>> Changes in v4:
>> - Take Seungwon's suggestion and don't add any dw_mmc-pltfm code.
>> Changes in v3:
>> - Add freeze/thaw and poweroff/restore noirq entries.
>> Changes in v2:
>> - Use suspend_noirq as per James Hogan.
>> drivers/mmc/host/dw_mmc-exynos.c | 51 ++++++++++++++++++++++++++++++++++++++--
>> 1 file changed, 49 insertions(+), 2 deletions(-)
>> diff --git a/drivers/mmc/host/dw_mmc-exynos.c b/drivers/mmc/host/dw_mmc-exynos.c
>> index 866edef..0c1f192 100644
>> --- a/drivers/mmc/host/dw_mmc-exynos.c
>> +++ b/drivers/mmc/host/dw_mmc-exynos.c
>> @@ -30,6 +30,7 @@
>> #define SDMMC_CLKSEL_TIMING(x, y, z) (SDMMC_CLKSEL_CCLK_SAMPLE(x) | \
>> SDMMC_CLKSEL_CCLK_DRIVE(y) | \
>> +#define SDMMC_CLKSEL_WAKEUP_INT BIT(11)
>> #define EXYNOS4210_FIXED_CIU_CLK_DIV 2
>> #define EXYNOS4412_FIXED_CIU_CLK_DIV 4
>> @@ -100,6 +101,30 @@ static int dw_mci_exynos_setup_clock(struct dw_mci *host)
>> return 0;
>> + * dw_mci_exynos_resume_noirq - Exynos-specific resume code
>> + *
>> + * On exynos5420 there is a silicon errata that will sometimes leave the
>> + * WAKEUP_INT bit in the CLKSEL register asserted. This bit is 1 to indicate
>> + * that it fired and we can clear it by writing a 1 back. Clear it to prevent
>> + * interrupts from going off constantly.
>> + *
>> + * We run this code on all exynos variants because it doesn't hurt and the bug
>> + * may be more widespread than just exynos5420.
> I guess just above comment can be removed. (Not be widespread)
> Updating the origin value of CLKSEL looks like no harm while SDMMC_CLKSEL_WAKEUP_INT is cleared.
OK, no problem. I'll clean up the comment next time revision.
>> +static int __init dw_mci_exynos_init(void)
>> + /* Add a "noirq" resume to platform pmops */
>> + memcpy(&dw_mci_exynos_pmops, &dw_mci_pltfm_pmops,
>> + sizeof(dw_mci_exynos_pmops));
>> + WARN_ON(dw_mci_exynos_pmops.resume_noirq ||
>> + dw_mci_exynos_pmops.thaw_noirq ||
>> + dw_mci_exynos_pmops.restore_noirq);
>> + dw_mci_exynos_pmops.resume_noirq = dw_mci_exynos_resume_noirq;
>> + dw_mci_exynos_pmops.thaw_noirq = dw_mci_exynos_resume_noirq;
>> + dw_mci_exynos_pmops.restore_noirq = dw_mci_exynos_resume_noirq;
> If CONFIG_PM_SLEEP is not defined, we don't need to add it.
> And also, instead of reusing dw_mci_pltfm_pmops, how about defining dw_mci_exynos_pmops's own?
> Of course, suspend/resume will not different with dw_mci_pltfm* just now.
> But specific code for exynos would be added soon.
Whoops! ...of course this should be conditional on CONFIG_PM_SLEEP.
Thank you for catching.
I spent a bit of time debating whether I should make my own structure
or do a copy like this. It felt like a bit of a toss up to me, but
I'm happy to do it the other way. I will call dw_mci_suspend(host)
directly and assume hope that nobody adds any important code to
dw_mci_pltfm_suspend(). The other alternative would be make
dw_mci_pltfm_suspend() exported or call it indirectly through
dw_mci_pltfm_pmops, both of which seem slightly worse.
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