Hi Marek, On 12 June 2018 at 10:28, Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> wrote: > Hi Ulf, > > On 2018-06-11 14:24, Ulf Hansson wrote: >> On 11 June 2018 at 11:50, Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> wrote: >>> On 2018-06-11 11:35, Ulf Hansson wrote: >>>> On 11 June 2018 at 08:48, Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> wrote: >>>>> dw_mci_exynos_resume_noirq() performs DWMMC register access without >>>>> ensuring that respective clocks are enabled. This might cause external >>>>> abort on some systems (observed on Exynos5433 based boards). Fix this >>>>> by adding needed prepare_enable/disable_unprepare calls. >>>>> >>>>> Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> >>>>> --- >>>>> drivers/mmc/host/dw_mmc-exynos.c | 6 ++++++ >>>>> 1 file changed, 6 insertions(+) >>>>> >>>>> diff --git a/drivers/mmc/host/dw_mmc-exynos.c b/drivers/mmc/host/dw_mmc-exynos.c >>>>> index 3164681108ae..6125b68726b0 100644 >>>>> --- a/drivers/mmc/host/dw_mmc-exynos.c >>>>> +++ b/drivers/mmc/host/dw_mmc-exynos.c >>>>> @@ -193,6 +193,9 @@ static int dw_mci_exynos_resume_noirq(struct device *dev) >>>>> struct dw_mci_exynos_priv_data *priv = host->priv; >>>>> u32 clksel; >>>>> >>>>> + clk_prepare_enable(host->biu_clk); >>>>> + clk_prepare_enable(host->ciu_clk); >>>>> + >>>>> if (priv->ctrl_type == DW_MCI_TYPE_EXYNOS7 || >>>>> priv->ctrl_type == DW_MCI_TYPE_EXYNOS7_SMU) >>>>> clksel = mci_readl(host, CLKSEL64); >>>>> @@ -207,6 +210,9 @@ static int dw_mci_exynos_resume_noirq(struct device *dev) >>>>> mci_writel(host, CLKSEL, clksel); >>>>> } >>>>> >>>>> + clk_disable_unprepare(host->biu_clk); >>>>> + clk_disable_unprepare(host->ciu_clk); >>>>> + >>>>> return 0; >>>>> } >>>>> #else >>>> I looked a little closer and I am wondering if it wouldn't be possible >>>> to use SET_NOIRQ_SYSTEM_SLEEP_PM_OPS() instead of >>>> SET_SYSTEM_SLEEP_PM_OPS()? >>>> >>>> Somelike this: >>>> SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend, >>>> dw_mci_exynos_resume_noirq) >>>> >>>> Then from dw_mci_exynos_resume_noirq() call pm_runtime_force_resume(). >>>> >>>> I think it would simplify the code a bit, as you can rely on the >>>> runtime PM callbacks to deal with clk_prepare_enable() and >>>> clk_disable_unprepare(), unless I am mistaken. >>> This will not fix the problem, because mci_writel() calls in >>> dw_mci_exynos_resume_noirq are done unconditionally, regardless of the >>> controller's runtime pm state. Since commit 1d9174fbc55e after calling >>> pm_runtime_force_resume() there is no guarantee that device is in >>> runtime active state if it was runtime suspended state. >> Yes, because the runtime PM usage count is greater than 1. >> (pm_runtime_get_noresume() is called during probe). >> >> If you want to make this explicit (not relying on ->probe()), one can >> add a ->suspend_noirq() callback and call pm_runtime_get_noresume() in >> it. > > Sorry, but I don't get how this would work. Exactly the same pattern as > you have proposed was already used in s3c-64xx SPI driver and it didn't > work properly (tested on the same SoC as this DW-MMC change). I had to > move register access to runtime resume callback to fix external abort > issue: > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e935dba111621bd6a0c5d48e6511a4d9885103b4 Yep, that is a correct solution. > > Here in DW-MMC driver such approach (moving all the code to runtime > resume callback) is not possible because of the potential interrupt storm > caused by the hw bug (that's the reason of using noirq resume callback). I understand. What you need is to run the runtime resume/suspend callbacks in the resume/suspend noirq phase. Moreover, you need to make sure that the runtime resume callback, really becomes invoked during the resume noirq phase, because of the HW bug. I think the below should work. Can you give it a try? It relies on the call pm_runtime_get_noresume(), done during ->probe(). Note that, the driver always keeps the RPM usage count increased, thus preventing runtime suspend during normal execution. Anyway, if this doesn't work, your suggested approach works fine as well. --- drivers/mmc/host/dw_mmc-exynos.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) diff --git a/drivers/mmc/host/dw_mmc-exynos.c b/drivers/mmc/host/dw_mmc-exynos.c index a84aa3f1ae85..66132f7fceed 100644 --- a/drivers/mmc/host/dw_mmc-exynos.c +++ b/drivers/mmc/host/dw_mmc-exynos.c @@ -175,7 +175,9 @@ static int dw_mci_exynos_runtime_resume(struct device *dev) return ret; } +#endif /* CONFIG_PM */ +#ifdef CONFIG_PM_SLEEP /** * dw_mci_exynos_resume_noirq - Exynos-specific resume code * @@ -193,6 +195,8 @@ static int dw_mci_exynos_resume_noirq(struct device *dev) struct dw_mci_exynos_priv_data *priv = host->priv; u32 clksel; + pm_runtime_force_resume(dev); + if (priv->ctrl_type == DW_MCI_TYPE_EXYNOS7 || priv->ctrl_type == DW_MCI_TYPE_EXYNOS7_SMU) clksel = mci_readl(host, CLKSEL64); @@ -209,9 +213,7 @@ static int dw_mci_exynos_resume_noirq(struct device *dev) return 0; } -#else -#define dw_mci_exynos_resume_noirq NULL -#endif /* CONFIG_PM */ +#endif /* CONFIG_PM_SLEEP */ static void dw_mci_exynos_config_hs400(struct dw_mci *host, u32 timing) { @@ -553,14 +555,11 @@ static int dw_mci_exynos_remove(struct platform_device *pdev) } static const struct dev_pm_ops dw_mci_exynos_pmops = { - SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend, - pm_runtime_force_resume) + SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend, + dw_mci_exynos_resume_noirq) SET_RUNTIME_PM_OPS(dw_mci_runtime_suspend, dw_mci_exynos_runtime_resume, NULL) - .resume_noirq = dw_mci_exynos_resume_noirq, - .thaw_noirq = dw_mci_exynos_resume_noirq, - .restore_noirq = dw_mci_exynos_resume_noirq, }; static struct platform_driver dw_mci_exynos_pltfm_driver = { -- Kind regards Uffe -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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