linux-kernel - Re: [PATCH v2 10/15] soc: qcom: ipa: use new module_firmware

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Message-ID: <0b159c53-57a6-b771-04ab-2a76c45d0ef4@ieee.org>
Date:   Tue, 19 May 2020 17:34:13 -0500
From:   Alex Elder <elder@...e.org>
To:     Luis Chamberlain <mcgrof@...nel.org>, jeyu@...nel.org
Cc:     akpm@...ux-foundation.org, arnd@...db.de, rostedt@...dmis.org,
        mingo@...hat.com, aquini@...hat.com, cai@....pw, dyoung@...hat.com,
        bhe@...hat.com, peterz@...radead.org, tglx@...utronix.de,
        gpiccoli@...onical.com, pmladek@...e.com, tiwai@...e.de,
        schlad@...e.de, andriy.shevchenko@...ux.intel.com,
        keescook@...omium.org, daniel.vetter@...ll.ch, will@...nel.org,
        mchehab+samsung@...nel.org, kvalo@...eaurora.org,
        davem@...emloft.net, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Alex Elder <elder@...nel.org>
Subject: Re: [PATCH v2 10/15] soc: qcom: ipa: use new
 module_firmware_crashed()

On 5/15/20 4:28 PM, Luis Chamberlain wrote:
> This makes use of the new module_firmware_crashed() to help
> annotate when firmware for device drivers crash. When firmware
> crashes devices can sometimes become unresponsive, and recovery
> sometimes requires a driver unload / reload and in the worst cases
> a reboot.
> 
> Using a taint flag allows us to annotate when this happens clearly.

I don't fully understand what this is meant to do, so I can't
fully assess whether it's the right thing to do.

But in this particular place in the IPA code, the *modem* has
crashed.  And the IPA driver is not responsible for modem
firmware, remoteproc is.

The IPA driver *can* be responsible for loading some other
firmware, but even in that case, it only happens on initial
boot, and it's basically assumed to never crash.

So regardless of whether this module_firmware_crashed() call is
appropriate in some places, I believe it should not be used here.

					-Alex

> 
> Cc: Alex Elder <elder@...nel.org>
> Signed-off-by: Luis Chamberlain <mcgrof@...nel.org>
> ---
>   drivers/net/ipa/ipa_modem.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/net/ipa/ipa_modem.c b/drivers/net/ipa/ipa_modem.c
> index ed10818dd99f..1790b87446ed 100644
> --- a/drivers/net/ipa/ipa_modem.c
> +++ b/drivers/net/ipa/ipa_modem.c
> @@ -285,6 +285,7 @@ static void ipa_modem_crashed(struct ipa *ipa)
>   	struct device *dev = &ipa->pdev->dev;
>   	int ret;
>   
> +	module_firmware_crashed();
>   	ipa_endpoint_modem_pause_all(ipa, true);
>   
>   	ipa_endpoint_modem_hol_block_clear_all(ipa);
>