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([2600:8803:e7e4:1d00:79a:b8ae:edee:ec5]) by smtp.gmail.com with ESMTPSA id 586e51a60fabf-2d5212c95ebsm1040778fac.5.2025.04.19.11.07.25 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 19 Apr 2025 11:07:26 -0700 (PDT) Message-ID: <9cdc7053-ae22-4ad5-801c-46df7398ebf9@baylibre.com> Date: Sat, 19 Apr 2025 13:07:25 -0500 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] iio: amplifiers: ada4250: use DMA-safe memory for regmap_bulk_read() To: Andy Shevchenko Cc: Antoniu Miclaus , Lars-Peter Clausen , Michael Hennerich , Jonathan Cameron , =?UTF-8?Q?Nuno_S=C3=A1?= , Jonathan Cameron , "linux-iio@vger.kernel.org" , "linux-kernel@vger.kernel.org" References: <20250418-iio-amplifiers-ada4250-simplify-data-buffer-in-init-v1-1-7e7bd6dad423@baylibre.com> From: David Lechner Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 > 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?