On Wed, Jul 04, 2018 at 03:34:36PM +0200, Ulf Hansson wrote:

On 4 July 2018 at 13:34, Marc Zyngier [off-list ref] wrote:

quoted

On 04/07/18 11:50, Ulf Hansson wrote:

quoted

+ Marc

On 4 July 2018 at 08:28, Stefan Mavrodiev [off-list ref] wrote:

quoted

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@olimex.com>
---
 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).

That's the problem. This may work on some SoCs but not on others.

I don't really expect that driver to be used on some other SoCs, and
if that ever happens, maybe we can fix it when it does?

Maxime

-- 
Maxime Ripard, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com
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