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[82.192.45.213]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-47be3ac5409sm75866275e9.15.2025.12.21.07.57.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 21 Dec 2025 07:57:08 -0800 (PST) From: Jernej =?UTF-8?B?xaBrcmFiZWM=?= To: Vinod Koul , Chen-Yu Tsai , Jernej Skrabec , Samuel Holland , Chen-Yu Tsai Cc: Andre Przywara , dmaengine@vger.kernel.org, linux-sunxi@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] dmaengine: sun6i: Choose appropriate burst length under maxburst Date: Sun, 21 Dec 2025 16:57:07 +0100 Message-ID: <3385264.aeNJFYEL58@jernej-laptop> In-Reply-To: <20251221080450.1813479-1-wens@kernel.org> References: <20251221080450.1813479-1-wens@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251221_075710_760028_CED11F9A X-CRM114-Status: GOOD ( 11.48 ) 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 Dne nedelja, 21. december 2025 ob 09:04:48 Srednjeevropski standardni =C4= =8Das je Chen-Yu Tsai napisal(a): > maxburst, as provided by the client, specifies the largest amount of > data that is allowed to be transferred in one burst. This limit is > normally provided to avoid a data burst overflowing the target FIFO. > It does not mean that the DMA engine can only do bursts in that size. >=20 > Let the driver pick the largest supported burst length within the > given limit. This lets the driver work correctly with some clients that > give a large maxburst value. In particular, the 8250_dw driver will give > a quarter of the UART's FIFO size as maxburst. On some systems the FIFO > size is 256 bytes, giving a maxburst of 64 bytes, while the hardware > only supports bursts of up to 16 bytes. >=20 > Signed-off-by: Chen-Yu Tsai Reviewed-by: Jernej Skrabec Best regards, Jernej