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 A5EE713AC5 for ; Mon, 26 Jun 2023 18:27:10 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B3394C433C8; Mon, 26 Jun 2023 18:27:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1687804030; bh=En6cyVhig4P71uvHOkeVN2rB/1pzjjQFS9+3GOfF+0A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=2JaBT4GIESkWTzUHLmNTX0+xxlgNfzChpLKwOkYzq8SYBqqqEz7N5/CgljW3BRu0k 1eTnMv8CYHr2kIkHxcfONLOmtY1mIfFVW570LWwxhrL4arQgQlQsH9e4r/72o9/XBx EMhZx/4SnzSupEbz2p9XcXut5/MPw4BOaDHGd/Fc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable , Robert Hodaszi , Sasha Levin Subject: [PATCH 6.1 005/170] tty: serial: fsl_lpuart: reduce RX watermark to 0 on LS1028A Date: Mon, 26 Jun 2023 20:09:34 +0200 Message-ID: <20230626180800.743009302@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230626180800.476539630@linuxfoundation.org> References: <20230626180800.476539630@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 82066f17bdfb1..1093c74b52840 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -302,7 +302,7 @@ 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 = { -- 2.39.2