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([179.179.237.181]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-15d7234c2a2sm10735006c88.0.2026.10.06.04.33.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 06 Oct 2026 04:33:20 -0700 (PDT) From: Vinicius Pedrosa To: Andre Przywara , linux-serial@vger.kernel.org Cc: gregkh@linuxfoundation.org, jirislaby@kernel.org, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, andriy.shevchenko@linux.intel.com, ilpo.jarvinen@linux.intel.com, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-sunxi@lists.linux.dev, Enzo Adriano Subject: Re: [PATCH 3/3] serial: 8250_dw: Add Allwinner A733 UART Date: Tue, 6 Oct 2026 08:33:06 -0300 Message-ID: <20261006113307.86417-1-vinicius.eduardo.pedrosa@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: References: <20261005172538.398522-1-vinicius.eduardo.pedrosa@gmail.com> <20261005172538.398522-4-vinicius.eduardo.pedrosa@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Hi Andre, On 10/6/26 11:46, Andre Przywara wrote: > So I was wondering if we should refine the DLF detection instead? Only > when the readback from 0xc0 returns some 2^n-1 value we assume DLF is > implemented? Thanks, that's better than a per-SoC quirk. On the A7Z, writing all ones to 0xc0 reads back 0x19f, so the same family as your 0x9f with bit 8 on top. A 2^n - 1 check rejects it. With the check on the board, dlf_size is 0 and 0xc0 is still 0 after the termios stress loop. Without it, 0xc0 reads 0xb after boot. I don't have a UART with a real DLF to try. v2 puts the check in its own patch and keeps the fallback, with the A733 compatible only selecting SKIP_SET_RATE. On the fallback alone the same loop leaves 28 garbage bytes in 3000 lines. The probe itself still writes all ones to 0xc0 before restoring it. Would you rather skip that with a DT property, or leave it? Thanks, Vinicius