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 D9D555381 for ; Mon, 19 Jun 2023 10:37:18 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 637E5C433C0; Mon, 19 Jun 2023 10:37:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1687171038; bh=/MPlHWjlQW5MauXPUuGP9Q+pqdMIAd0lNprvRFnitZM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gO4ADa5ZyON2VkLLWijR3WxVOmCf4VpKMsyXySSuwdGCp1+uXD+g5rNcjWoZMlZ3J x2Y6d7sZzJwZVsZf4IQt3185eNNEyo4za+C9Wju5xwYt+KS+uq42QkbsXyC7yOhg+A Bh1FAOyi2o/nWm9EzX4+DV8xXravvXXpqLU23E+Y= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable , Robert Hodaszi Subject: [PATCH 6.3 099/187] tty: serial: fsl_lpuart: reduce RX watermark to 0 on LS1028A Date: Mon, 19 Jun 2023 12:28:37 +0200 Message-ID: <20230619102202.386067478@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230619102157.579823843@linuxfoundation.org> References: <20230619102157.579823843@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 commit a82c3df955f8c1c726e4976527aa6ae924a67dd9 upstream. 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 --- drivers/tty/serial/fsl_lpuart.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -310,7 +310,7 @@ static const struct lpuart_soc_data ls10 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 = {