linux-kernel - Re: [PATCH v2] i2c: tegra: Wait for config load atomically while in ISR

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Date:   Tue, 12 Jan 2021 09:48:20 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Mikko Perttunen <mperttunen@...dia.com>, ldewangan@...dia.com,
        thierry.reding@...il.com, jonathanh@...dia.com, wsa@...nel.org
Cc:     linux-i2c@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH v2] i2c: tegra: Wait for config load atomically while in
 ISR

11.01.2021 22:31, Dmitry Osipenko пишет:
> 11.01.2021 19:08, Mikko Perttunen пишет:
>> Upon a communication error, the interrupt handler can call
>> tegra_i2c_disable_packet_mode. This causes a sleeping poll to happen
>> unless the current transaction was marked atomic. Fix this by
>> making the poll happen atomically if we are in an IRQ.
>>
>> This matches the behavior prior to the patch mentioned
>> in the Fixes tag.
>>
>> Fixes: ede2299f7101 ("i2c: tegra: Support atomic transfers")
>> Cc: stable@...r.kernel.org
>> Signed-off-by: Mikko Perttunen <mperttunen@...dia.com>
>> ---
>> v2:
>> * Use in_irq() instead of passing a flag from the ISR.
>>   Thanks to Dmitry for the suggestion.
>> * Update commit message.
>> ---
>>  drivers/i2c/busses/i2c-tegra.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
>> index 6f08c0c3238d..0727383f4940 100644
>> --- a/drivers/i2c/busses/i2c-tegra.c
>> +++ b/drivers/i2c/busses/i2c-tegra.c
>> @@ -533,7 +533,7 @@ static int tegra_i2c_poll_register(struct tegra_i2c_dev *i2c_dev,
>>  	void __iomem *addr = i2c_dev->base + tegra_i2c_reg_addr(i2c_dev, reg);
>>  	u32 val;
>>  
>> -	if (!i2c_dev->atomic_mode)
>> +	if (!i2c_dev->atomic_mode && !in_irq())
>>  		return readl_relaxed_poll_timeout(addr, val, !(val & mask),
>>  						  delay_us, timeout_us);
>>  
>>
> 
> Reviewed-by: Dmitry Osipenko <digetx@...il.com>
> 

Perhaps a follow up change could be to use a threaded interrupt context,
I'll type a patch for that.