linux-kernel - Re: Issue with Broadcom wireless in 5.2rc1 (was Re: [PATCH] mmc: sdhci: queue work after sdhci_defer

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Message-ID: <af4d6703-8506-dad7-c2ed-13fa8b2e390d@broadcom.com>
Date:   Tue, 4 Jun 2019 13:33:18 +0200
From:   Arend Van Spriel <arend.vanspriel@...adcom.com>
To:     Adrian Hunter <adrian.hunter@...el.com>,
        Brian Masney <masneyb@...tation.org>
Cc:     Franky Lin <franky.lin@...adcom.com>,
        Hante Meuleman <hante.meuleman@...adcom.com>,
        Chi-Hsien Lin <chi-hsien.lin@...ress.com>,
        Wright Feng <wright.feng@...ress.com>, ulf.hansson@...aro.org,
        faiz_abbas@...com, linux-mmc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        Kalle Valo <kvalo@...eaurora.org>,
        linux-wireless@...r.kernel.org,
        brcm80211-dev-list.pdl@...adcom.com,
        brcm80211-dev-list@...ress.com, netdev@...r.kernel.org
Subject: Re: Issue with Broadcom wireless in 5.2rc1 (was Re: [PATCH] mmc:
 sdhci: queue work after sdhci_defer_done())

On 5/27/2019 2:08 PM, Adrian Hunter wrote:
> On 27/05/19 12:37 PM, Brian Masney wrote:
>> On Sun, May 26, 2019 at 03:58:19PM -0400, Brian Masney wrote:
>>> I attached a patch that shows how I was able to determine what had
>>> already claimed the host.
>> On Mon, May 27, 2019 at 10:48:24AM +0300, Adrian Hunter wrote:
>>> 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.
> 
> Please try the patch below:

Finally got time to update my kernel to 5.2-rc2. This patch indeed 
resolves the issue.

Thanks,
Arend