On Wed, Jul 04, 2018 at 12:34:01PM +0100, Marc Zyngier wrote:
> On 04/07/18 11:50, Ulf Hansson wrote:
> > + Marc
> >
> > On 4 July 2018 at 08:28, Stefan Mavrodiev <stefan@xxxxxxxxxx> wrote:
> >> When mmc host controller enters suspend state, the clocks are
> >> disabled, but irqs are not. For some reason the irqchip emits
> >> false interrupts, which causes system lock loop.
> >>
> >> Debug log is:
> >> ...
> >> sunxi-mmc 1c11000.mmc: setting clk to 52000000, rounded 51200000
> >> sunxi-mmc 1c11000.mmc: enabling the clock
> >> sunxi-mmc 1c11000.mmc: cmd 13(8000014d) arg 10000 ie 0x0000bbc6 len 0
> >> sunxi-mmc 1c11000.mmc: irq: rq (ptrval) mi 00000004 idi 00000000
> >> sunxi-mmc 1c11000.mmc: cmd 6(80000146) arg 3210101 ie 0x0000bbc6 len 0
> >> sunxi-mmc 1c11000.mmc: irq: rq (ptrval) mi 00000004 idi 00000000
> >> sunxi-mmc 1c11000.mmc: cmd 13(8000014d) arg 10000 ie 0x0000bbc6 len 0
> >> sunxi-mmc 1c11000.mmc: irq: rq (ptrval) mi 00000004 idi 00000000
> >> mmc1: new DDR MMC card at address 0001
> >> mmcblk1: mmc1:0001 AGND3R 14.6 GiB
> >> mmcblk1boot0: mmc1:0001 AGND3R partition 1 4.00 MiB
> >> mmcblk1boot1: mmc1:0001 AGND3R partition 2 4.00 MiB
> >> sunxi-mmc 1c11000.mmc: cmd 18(80003352) arg 0 ie 0x0000fbc2 len 409
> >> sunxi-mmc 1c11000.mmc: irq: rq (ptrval) mi 00004000 idi 00000002
> >> mmcblk1: p1
> >> sunxi-mmc 1c11000.mmc: irq: rq (null) mi 00000000 idi 00000000
> >> sunxi-mmc 1c11000.mmc: irq: rq (null) mi 00000000 idi 00000000
> >> sunxi-mmc 1c11000.mmc: irq: rq (null) mi 00000000 idi 00000000
> >> sunxi-mmc 1c11000.mmc: irq: rq (null) mi 00000000 idi 00000000
> >> and so on...
> >>
> >> This issue apears on eMMC cards, routed on MMC2 slot. The patch is
> >> tested with A20-OLinuXino-MICRO/LIME/LIME2 boards.
> >>
> >> Fixes: 9a8e1e8cc2c0 ("mmc: sunxi: Add runtime_pm support")
> >> Signed-off-by: Stefan Mavrodiev <stefan@xxxxxxxxxx>
> >> ---
> >> Changes in v2:
> >> - Add comment why disable_irq() is necessary
> >>
> >> ---
> >> drivers/mmc/host/sunxi-mmc.c | 7 +++++++
> >> 1 file changed, 7 insertions(+)
> >>
> >> diff --git a/drivers/mmc/host/sunxi-mmc.c b/drivers/mmc/host/sunxi-mmc.c
> >> index e747259..8e7f3e3 100644
> >> --- a/drivers/mmc/host/sunxi-mmc.c
> >> +++ b/drivers/mmc/host/sunxi-mmc.c
> >> @@ -1446,6 +1446,7 @@ static int sunxi_mmc_runtime_resume(struct device *dev)
> >> sunxi_mmc_init_host(host);
> >> sunxi_mmc_set_bus_width(host, mmc->ios.bus_width);
> >> sunxi_mmc_set_clk(host, &mmc->ios);
> >> + enable_irq(host->irq);
> >>
> >> return 0;
> >> }
> >> @@ -1455,6 +1456,12 @@ static int sunxi_mmc_runtime_suspend(struct device *dev)
> >> struct mmc_host *mmc = dev_get_drvdata(dev);
> >> struct sunxi_mmc_host *host = mmc_priv(mmc);
> >>
> >> + /*
> >> + * When clocks are off, it's possible receiving
> >> + * fake interrupts, which will stall the system.
> >> + * Disabling the irq will prevent this.
> >> + */
> >> + disable_irq(host->irq);
> >
> > No, this doesn't work for shared IRQs.
>
> Well, in this case, it does work, because that interrupt line cannot be
> shared with anything else, if I understand how the SoC is wired: each
> MMC controller has a dedicated interrupt line to the GIC, and it isn't
> shared with anything (that's on the A20 though, and I don't know about
> other SoCs integrating the same IP).
Yeah, and I've never seen a shared interrupt line within the Allwinner
SoCs, so I guess we're pretty safe from that regard.
Maxime
--
Maxime Ripard, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com
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