On 26/05/19 10:58 PM, Brian Masney wrote:

On Sun, May 26, 2019 at 08:42:21PM +0200, Arend Van Spriel wrote:

quoted

On 5/26/2019 2:21 PM, Brian Masney wrote:

quoted

+ Broadcom wireless maintainers

On Fri, May 24, 2019 at 11:49:58AM -0400, Brian Masney wrote:

quoted

On Fri, May 24, 2019 at 03:17:13PM +0300, Adrian Hunter wrote:

quoted

On 24/05/19 2:10 PM, Brian Masney wrote:

quoted

WiFi stopped working on the LG Nexus 5 phone and the issue was bisected
to the commit c07a48c26519 ("mmc: sdhci: Remove finish_tasklet") that
moved from using a tasklet to a work queue. That patch also changed
sdhci_irq() to return IRQ_WAKE_THREAD instead of finishing the work when
sdhci_defer_done() is true. Change it to queue work to the complete work
queue if sdhci_defer_done() is true so that the functionality is
equilivent to what was there when the finish_tasklet was present. This
corrects the WiFi breakage on the Nexus 5 phone.

Signed-off-by: Brian Masney <redacted>
Fixes: c07a48c26519 ("mmc: sdhci: Remove finish_tasklet")
---
[ ... ]

  drivers/mmc/host/sdhci.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 97158344b862..3563c3bc57c9 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c

@@ -3115,7 +3115,7 @@ static irqreturn_t sdhci_irq(int irq, void *dev_id)
  			continue;
  		if (sdhci_defer_done(host, mrq)) {
-			result = IRQ_WAKE_THREAD;
+			queue_work(host->complete_wq, &host->complete_work);

The IRQ thread has a lot less latency than the work queue, which is why it
is done that way.

I am not sure why you say this change is equivalent to what was there
before, nor why it fixes your problem.

Can you explain some more?

[ ... ]

drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c calls
sdio_claim_host() and it appears to never return.

This is because SDHCI is using the IRQ thread to process the SDIO card
interrupt (sdio_run_irqs()).  When the card driver tries to use the card, it
causes interrupts which deadlocks since c07a48c26519 ("mmc: sdhci: Remove
finish_tasklet") has moved the tasklet processing to the IRQ thread.

I would expect to be able to use the IRQ thread to complete requests, and it
is desirable to do so because it is lower latency.

Probably, SDHCI should use sdio_signal_irq() which queues a work item, and
is what other drivers are doing.

I will investigate some more and send a patch.