Re: [PATCH] iio: amplifiers: ada4250: use DMA-safe memory for regmap_bulk_read()

David Lechner
2025-04-19T18:07:28Z

On 4/19/25 10:03 AM, Andy Shevchenko wrote:
> On Fri, Apr 18, 2025 at 02:09:04PM -0500, David Lechner wrote:
>> On 4/18/25 1:58 PM, Andy Shevchenko wrote:
>>> пʼятниця, 18 квітня 2025 р. David Lechner <dlechner@baylibre.com <mailto:dlechner@baylibre.com>> пише:
>>>
>>> Use DMA-safe memory instead of stack-allocated memory for the call to
>>> regmap_bulk_read() in the ada4250_init() function as this could be used
>>> directly by a SPI controller.
>>>
>>> Sorry, but can you elaborate more on this? If driver doesn’t override the
>>> callbacks the regmap SPI uses spi_write_then_read() which is supposed to be
>>> dma safe.
>>
>> Ah, I didn't dig that far down. Will send a new patch that just cleans up the
>> unnecessary alignment and unaligned call.
>
> But do you have a real life issue with that? Coincidentally we discussed
> similar case in another driver with colleague of mine, and he insists that it
> might be still broken (somewhere).
>

Some drivers that use regmap with SPI implement their own read and write
callbacks if the default one doesn't work, so maybe something like that?