linux-kernel - Re: [PATCH] spi: tegra114: Don't fail set_cs

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Message-ID: <ea5f8416-64da-4a26-8706-bc7ace502ad1@nvidia.com>
Date: Tue, 6 May 2025 11:06:35 +0100
From: Jon Hunter <jonathanh@...dia.com>
To: Aaron Kling <webgeek1234@...il.com>
Cc: Laxman Dewangan <ldewangan@...dia.com>, Mark Brown <broonie@...nel.org>,
 Thierry Reding <thierry.reding@...il.com>,
 Mason Zhang <Mason.Zhang@...iatek.com>, linux-spi@...r.kernel.org,
 linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org,
 stable@...r.kernel.org
Subject: Re: [PATCH] spi: tegra114: Don't fail set_cs_timing when delays are
 zero


On 06/05/2025 10:50, Aaron Kling wrote:

...

>>> -     if (setup->unit != SPI_DELAY_UNIT_SCK ||
>>> -         hold->unit != SPI_DELAY_UNIT_SCK ||
>>> -         inactive->unit != SPI_DELAY_UNIT_SCK) {
>>> +     if ((setup->unit && setup->unit != SPI_DELAY_UNIT_SCK) ||
>>> +         (hold->unit && hold->unit != SPI_DELAY_UNIT_SCK) ||
>>> +         (inactive->unit && inactive->unit != SPI_DELAY_UNIT_SCK)) {
>>
>> The above does not look correct to me. For example, if 'setup->unit' is
>> 0, this means that the unit is 'SPI_DELAY_UNIT_USECS' and does not
>> indicate that the delay is 0.
>>
>> Shouldn't the above be ...
>>
>>    if ((setup && setup->unit != SPI_DELAY_UNIT_SCK) ||
>>        (hold && hold->unit != SPI_DELAY_UNIT_SCK) ||
>>        (inactive && inactive->unit != SPI_DELAY_UNIT_SCK)) {
> 
> This is what the code looked like before 373c36b [0], which dropped
> that check because the pointers can never be NULL. Should this check
> if ->value is not 0 instead?

What the code does now does not match what you describe and does not 
appear to be correct. Yes checking ->value is not 0 would make sense.

Jon

-- 
nvpublic