From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D2BC911C86 for ; Thu, 24 Aug 2023 14:53:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4F757C433C8; Thu, 24 Aug 2023 14:53:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1692888832; bh=TnSQNfJjtZpEtwGHZo4/vFEpZdMFubugz2UFd2biJVs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ALgCv+6HXA8AXAxfq7b0GgEjbyBGQHTdLlWYY/oLmKXIuPbmO5dmhukBXUh4YxevY pgMU1y99FwyPz0llAMmZs6DmlIw8Fo4sLqsvNPs8FVCQNpleAq8+jBmZeIkS3vYocF gScL8ljo0yY+81KNjJImmt/WPC6B2VvRl1+BfzS0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable , Robert Hodaszi , Sasha Levin Subject: [PATCH 5.15 058/139] tty: serial: fsl_lpuart: reduce RX watermark to 0 on LS1028A Date: Thu, 24 Aug 2023 16:49:41 +0200 Message-ID: <20230824145026.144990676@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20230824145023.559380953@linuxfoundation.org> References: <20230824145023.559380953@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Robert Hodaszi [ Upstream commit a82c3df955f8c1c726e4976527aa6ae924a67dd9 ] LS1028A is using DMA with LPUART. Having RX watermark set to 1, means DMA transactions are started only after receiving the second character. On other platforms with newer LPUART IP, Receiver Idle Empty function initiates the DMA request after the receiver is idling for 4 characters. But this feature is missing on LS1028A, which is causing a 1-character delay in the RX direction on this platform. Set RX watermark to 0 to initiate RX DMA after each character. Link: https://lore.kernel.org/linux-serial/20230607103459.1222426-1-robert.hodaszi@digi.com/ Fixes: 9ad9df844754 ("tty: serial: fsl_lpuart: Fix the wrong RXWATER setting for rx dma case") Cc: stable Signed-off-by: Robert Hodaszi Message-ID: <20230609121334.1878626-1-robert.hodaszi@digi.com> Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/tty/serial/fsl_lpuart.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index 380d9237989b2..74b445fb065bd 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -300,7 +300,7 @@ static const struct lpuart_soc_data ls1021a_data = { static const struct lpuart_soc_data ls1028a_data = { .devtype = LS1028A_LPUART, .iotype = UPIO_MEM32, - .rx_watermark = 1, + .rx_watermark = 0, }; static struct lpuart_soc_data imx7ulp_data = { -- 2.40.1