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Wed, 30 Sep 2026 04:24:54 -0700 (PDT) Received: from [127.0.1.1] ([92.241.26.38]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4a01cd002bcsm3626105e9.4.2026.09.30.04.24.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 30 Sep 2026 04:24:53 -0700 (PDT) From: Fil Dunsky To: Arnd Bergmann Subject: Re: [PATCH RFC 07/10] tty: serial: Add Cortina Systems CS75xx UART driver In-Reply-To: <1d81c2ef-7a5b-4306-83d2-ff96b0eb6a06@app.fastmail.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> Date: Wed, 30 Sep 2026 14:24:51 +0300 Message-ID: <179076749140.3134070.3869742286743401078@gmail.com> Content-Transfer-Encoding: 8bit MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format="fixed" 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 , Jason Li X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260930_042456_826841_B0776043 X-CRM114-Status: GOOD ( 19.02 ) 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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). >> 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. I can only test on the CS7542. Jason, would you be fine with adding the CA82xx on top of this driver instead of a separate one? I am happy to add the compatible and the bits you need if you can test them. Thanks, Fil