diff mbox series

[1/2] mmc: tmio: Further fixup runtime PM management at remove

Message ID 20200515140445.15218-1-ulf.hansson@linaro.org
State Superseded
Headers show
Series [1/2] mmc: tmio: Further fixup runtime PM management at remove | expand

Commit Message

Ulf Hansson May 15, 2020, 2:04 p.m. UTC
Before calling tmio_mmc_host_probe(), the caller is required to enable
clocks for its device, as to make it accessible when reading/writing
registers during probe.

Therefore, the responsibility to disable these clocks, in the error path of
->probe() and during ->remove(), is better managed outside
tmio_mmc_host_remove(). As a matter of fact, callers of
tmio_mmc_host_remove() already expects this to be the behaviour.

However, there's a problem with tmio_mmc_host_remove() when the Kconfig
option, CONFIG_PM, is set. More precisely, tmio_mmc_host_remove() may then
disable the clock via runtime PM, which leads to clock enable/disable
imbalance problems, when the caller of tmio_mmc_host_remove() also tries to
disable the same clocks.

Reported-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

---
 drivers/mmc/host/tmio_mmc_core.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

-- 
2.20.1

Comments

Wolfram Sang May 18, 2020, 8:02 p.m. UTC | #1
On Fri, May 15, 2020 at 05:02:08PM +0200, Ulf Hansson wrote:
> On Fri, 15 May 2020 at 16:04, Ulf Hansson <ulf.hansson@linaro.org> wrote:
> >
> > Before calling tmio_mmc_host_probe(), the caller is required to enable
> > clocks for its device, as to make it accessible when reading/writing
> > registers during probe.
> >
> > Therefore, the responsibility to disable these clocks, in the error path of
> > ->probe() and during ->remove(), is better managed outside
> > tmio_mmc_host_remove(). As a matter of fact, callers of
> > tmio_mmc_host_remove() already expects this to be the behaviour.
> >
> > However, there's a problem with tmio_mmc_host_remove() when the Kconfig
> > option, CONFIG_PM, is set. More precisely, tmio_mmc_host_remove() may then
> > disable the clock via runtime PM, which leads to clock enable/disable
> > imbalance problems, when the caller of tmio_mmc_host_remove() also tries to
> > disable the same clocks.
> 
> Just realized that part of the commit message is missing, explaining
> the change. I intend to add this:
> 
> To solve the problem, let's make sure tmio_mmc_host_remove() leaves
> the device with clocks enabled, but also make sure to disable the
> IRQs, as we normally do at ->runtime_suspend().

Yeah, this paragraph is definately needed.

> Also, this is untested, so relying on you guys with the HW at hand.

I tested this on Gen3 M3-N (works fine!) and will next check your other
patch. If this is okay, too, I will check them on Gen2 tomorrow before I
give my Tested-by.

Ulf, thanks for working on this, too!
Wolfram Sang May 19, 2020, 1:56 p.m. UTC | #2
On Fri, May 15, 2020 at 04:04:45PM +0200, Ulf Hansson wrote:
> Before calling tmio_mmc_host_probe(), the caller is required to enable
> clocks for its device, as to make it accessible when reading/writing
> registers during probe.
> 
> Therefore, the responsibility to disable these clocks, in the error path of
> ->probe() and during ->remove(), is better managed outside
> tmio_mmc_host_remove(). As a matter of fact, callers of
> tmio_mmc_host_remove() already expects this to be the behaviour.
> 
> However, there's a problem with tmio_mmc_host_remove() when the Kconfig
> option, CONFIG_PM, is set. More precisely, tmio_mmc_host_remove() may then
> disable the clock via runtime PM, which leads to clock enable/disable
> imbalance problems, when the caller of tmio_mmc_host_remove() also tries to
> disable the same clocks.
> 
> Reported-by: Geert Uytterhoeven <geert+renesas@glider.be>
> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Works fine on my Lager board, too. Imbalance is gone when rebinding, and
I can access large files on the SD card.

Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
diff mbox series

Patch

diff --git a/drivers/mmc/host/tmio_mmc_core.c b/drivers/mmc/host/tmio_mmc_core.c
index f31afd1c2671..ba301fb7656b 100644
--- a/drivers/mmc/host/tmio_mmc_core.c
+++ b/drivers/mmc/host/tmio_mmc_core.c
@@ -1231,12 +1231,14 @@  void tmio_mmc_host_remove(struct tmio_mmc_host *host)
 	cancel_work_sync(&host->done);
 	cancel_delayed_work_sync(&host->delayed_reset_work);
 	tmio_mmc_release_dma(host);
+	tmio_mmc_disable_mmc_irqs(host, TMIO_MASK_ALL);
 
-	pm_runtime_dont_use_autosuspend(&pdev->dev);
 	if (host->native_hotplug)
 		pm_runtime_put_noidle(&pdev->dev);
-	pm_runtime_put_sync(&pdev->dev);
+
 	pm_runtime_disable(&pdev->dev);
+	pm_runtime_dont_use_autosuspend(&pdev->dev);
+	pm_runtime_put_noidle(&pdev->dev);
 }
 EXPORT_SYMBOL_GPL(tmio_mmc_host_remove);