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Mon, 04 Dec 2023 11:54:52 -0800 (PST) Date: Mon, 4 Dec 2023 14:54:00 -0500 From: Ben Wolsieffer To: Mark Brown Cc: linux-spi@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Maxime Coquelin , Alexandre Torgue , Alain Volmat Subject: Re: [PATCH] spi: stm32: enable controller before asserting CS Message-ID: References: <20231201214014.2539031-1-ben.wolsieffer@hefring.com> <9aa5e049-bd1c-41a6-b9b8-037ebb4f54b8@sirena.org.uk> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <9aa5e049-bd1c-41a6-b9b8-037ebb4f54b8@sirena.org.uk> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231204_115456_172826_5184E0D1 X-CRM114-Status: GOOD ( 33.11 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Dec 04, 2023 at 12:43:42PM +0000, Mark Brown wrote: > On Fri, Dec 01, 2023 at 06:11:36PM -0500, Ben Wolsieffer wrote: > > On Fri, Dec 01, 2023 at 09:50:33PM +0000, Mark Brown wrote: > > > On Fri, Dec 01, 2023 at 04:40:14PM -0500, Ben Wolsieffer wrote: > > > > This feels like it'd be a good fit for moving to runtime PM - that way > > > we avoid bouncing the controller on and off between messages which is > > > probably better anyway. The driver already does pinctrl management for > > > the device there. > > > Yes, that probably makes sense. There are a few bits that can only be > > configured while the controller is disabled, but it doesn't look like > > that applies to any of the ones set in stm32_spi_prepare_msg(). > > > I'm a little hesitant to make big changes to the driver since I can only > > test them on an STM32F7 though. > > It doesn't seem much more complex than what you're already proposing. I'm working on a new patch that uses runtime PM and will submit it soon. > > > It also occurs to me that this isn't going to work for devices which > > > chip select inverted - for them we can't stop driving chip select at all > > > since they need it held high when idle. There aren't that many such > > > devices and it'd loose us the PM which is rather awkward... I guess > > > that's an incremental issue with a more invasive fix though. > > > The driver only supports GPIO chip select rather than native, so I don't > > think this is a problem. Also, I don't think there's any difference > > So mentioning the drive seems a bit confusing then? Yes, I should have been more specific in the patch that only MOSI and CLK float when the controller is disabled and that CS remains driven. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel