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Wed, 30 Sep 2026 08:05:53 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ThreadId: AxcX56erMFXV Date: Wed, 30 Sep 2026 14:05:33 +0200 From: "Arnd Bergmann" To: "Fil Dunsky" Cc: "Linus Walleij" , "Krzysztof Kozlowski" , "Rob Herring" , "Krzysztof Kozlowski" , "Conor Dooley" , "Greg Kroah-Hartman" , "Jiri Slaby" , "Russell King" , "Alexandre Belloni" , "Drew Fustini" , "Lorenzo Pieralisi" , linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, "Jason Li" Message-Id: <9ad7be0e-6a60-4e7a-b94b-fd79ad0fc91c@app.fastmail.com> In-Reply-To: <179076749140.3134070.3869742286743401078@gmail.com> References: <20260930-b4-cs75xx-v1-0-4617c4463529@gmail.com> <20260930-b4-cs75xx-v1-7-4617c4463529@gmail.com> <1d81c2ef-7a5b-4306-83d2-ff96b0eb6a06@app.fastmail.com> <179076749140.3134070.3869742286743401078@gmail.com> Subject: Re: [PATCH RFC 07/10] tty: serial: Add Cortina Systems CS75xx UART driver Content-Type: text/plain Content-Transfer-Encoding: 7bit On Wed, Sep 30, 2026, at 13:24, Fil Dunsky wrote: > On Wed, Sep 30, 2026 at 01:08:07PM +0200, Arnd Bergmann wrote: >> On Wed, Sep 30, 2026, at 12:57, Linus Walleij wrote: >>> Look at this in your Linux tree: >>> git log -p b61c8bf4694b5115766849378dcb8787ff54e65e >>> >>> This is essentially a resurrection of that driver. >> >> Jason actually came back this summer to try again, see >> https://lore.kernel.org/linux-arm-kernel/20260610112821.3030099-1-jason.li@cortina-access.com/ > > Thanks, I was not aware of either. Comparing the two, it is the same > IP: the offsets of CFG, RX_SAMPLE, TX_DAT, RX_DAT, INFO, IE and INT > and the bit layout of CFG, INFO and the interrupt registers are > identical. The Cortina Access version additionally has a flow control > register at 0x04, RT_TUNE at 0x0c, STATUS at 0x2c and three more > interrupt causes (break, RX underrun, TX overrun). Ok, thanks for checking. >>> Anyways, clearly this driver is not just for CS75xx so name it >>> cortina-uart.c simply, and update symbols accordingly. Kconfig >>> should be SERIAL_CORTINA etc. >> >> I think we clearly want a driver that works for both the Cortina >> Systems CS75xx and the Cortina Access CA82xx, hopefully that >> would also support the ones inbetween (CS80xx, CA81xx). > > Agreed. For v2 I will rename it to drivers/tty/serial/cortina-uart.c > with SERIAL_CORTINA and SERIAL_CORTINA_CONSOLE, and name the binding > so that it can take the other parts. I would keep SoC specific > compatibles ("cortina,cs7542-uart", later e.g. > "cortina-access,ca8289-uart"), so that the flow control and the extra > interrupt causes can be enabled per compatible. Sounds good. The important bit here is to ensure the structure can work with both variants. Arnd