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 80FB91DFDAB; Fri, 25 Apr 2025 06:43:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745563408; cv=none; b=dgxcW0x5NZFANmF9VPPBzjpaqkf4HXrxbQx3QM9eo9GJP+XNSl9UIgn1op1JH6q7PBXKBp8YBGatQF9s7XC3kEcuJt5AGsNeMQsa3fTR6yQGH/AHI0nHaBz8dtcRWid88Oz1uVdsFRPawQnjAJQDcQTuub90VH5l81YgrDh3feQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745563408; c=relaxed/simple; bh=SEGWnTTOGRc1Xw/4NoMcbwV2WvKjpn/2lY/36Bzo9XU=; h=Message-ID:Date:MIME-Version:Subject:From:To:References: In-Reply-To:Content-Type; b=Q/aaIIFi6PRzdwtm540vrrXDNJeQ9f7qI7T7M+78GC3mep1pfrQ/Ucletkj9p24hAZJ2lzRn9166a/jE4yhsjWbrkFb8pPjaxB3MwQLYozfTFFRPH9qNjSG5gFUGkHVpgehHpnNehoo0bep3NeRF6wsNIHgSxrdXoZe6AqXFO6w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KJaCBl6z; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="KJaCBl6z" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 51104C4CEE4; Fri, 25 Apr 2025 06:43:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1745563408; bh=SEGWnTTOGRc1Xw/4NoMcbwV2WvKjpn/2lY/36Bzo9XU=; h=Date:Subject:From:To:References:In-Reply-To:From; b=KJaCBl6zQ99CG10igdZO3IHdUt60IdWeGEfAQXmggqPLHXcD68BxYzQh1mEXDrVtD nEQ5Bbr38CD3gBrYhOx74zK6vHejVKhnWyKAKBmCiieSlNFUhAy2tP0chbkN7MNfrJ KSMaMZp/iBHe95sFPzvT/cmn/mYvmL7TZSSn6kG324C6Xs23aQSpWZgii9b2P7NyHN chWJGsDFbDmpTF7Pg0IOYVHfjW/S9Lp+25D6k2llUnQ0NWuIoCLgHRcHx+FvTVeGOO S74Ncs32EwVrg1DTcoe92JtWBfi4BG/f5Qoli4jFrYxvLHtyQObIg7bjiYDcA5vZoQ /PMsCGpeNxfcg== Message-ID: <9d4e7002-48fe-4fa0-8e23-7c2160419910@kernel.org> Date: Fri, 25 Apr 2025 08:43:22 +0200 Precedence: bulk X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 4/4] serial: 8250_dw: fix PSLVERR on RX_TIMEOUT From: Jiri Slaby To: Yunhui Cui , arnd@arndb.de, andriy.shevchenko@linux.intel.com, benjamin.larsson@genexis.eu, gregkh@linuxfoundation.org, heikki.krogerus@linux.intel.com, ilpo.jarvinen@linux.intel.com, jkeeping@inmusicbrands.com, john.ogness@linutronix.de, linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, markus.mayer@linaro.org, matt.porter@linaro.org, namcao@linutronix.de, paulmck@kernel.org, pmladek@suse.com, schnelle@linux.ibm.com, sunilvl@ventanamicro.com, tim.kryger@linaro.org References: <20250425062425.68761-1-cuiyunhui@bytedance.com> <20250425062425.68761-4-cuiyunhui@bytedance.com> <57d75d55-81e3-445f-a705-e8c116281515@kernel.org> Content-Language: en-US Autocrypt: addr=jirislaby@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 25. 04. 25, 8:41, Jiri Slaby wrote: > On 25. 04. 25, 8:24, Yunhui Cui wrote: >> In the case of RX_TIMEOUT, to avoid PSLVERR, disable the FIFO >> before reading UART_RX when UART_LSR_DR is not set. >> >> Fixes: 424d79183af0 ("serial: 8250_dw: Avoid "too much work" from >> bogus rx timeout interrupt") >> Signed-off-by: Yunhui Cui >> --- >>   drivers/tty/serial/8250/8250_dw.c | 13 ++++++++++++- >>   1 file changed, 12 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/ >> serial/8250/8250_dw.c >> index 07f9be074b4b..1e364280a108 100644 >> --- a/drivers/tty/serial/8250/8250_dw.c >> +++ b/drivers/tty/serial/8250/8250_dw.c >> @@ -273,6 +273,7 @@ static int dw8250_handle_irq(struct uart_port *p) >>       unsigned int quirks = d->pdata->quirks; >>       unsigned int status; >>       unsigned long flags; >> +    unsigned char old_fcr; > > No more unsigned char, please. Use u8. > >> @@ -288,9 +289,19 @@ static int dw8250_handle_irq(struct uart_port *p) >>           uart_port_lock_irqsave(p, &flags); >>           status = serial_lsr_in(up); >> -        if (!(status & (UART_LSR_DR | UART_LSR_BI))) >> +        if (!(status & (UART_LSR_DR | UART_LSR_BI))) { >> +            /* To avoid PSLVERR, disable the FIFO first. */ >> +            if (up->fcr & UART_FCR_ENABLE_FIFO) { >> +                old_fcr = serial_in(up, UART_FCR); Wait, read(FCR) actually means read(IIR). FCR is write only. Or is DW special in this? >> +                serial_out(up, UART_FCR, old_fcr & ~1); > > s/1/UART_FCR_ENABLE_FIFO/ > >> +            } >> + >>               (void) p->serial_in(p, UART_RX); >> +            if (up->fcr & UART_FCR_ENABLE_FIFO) >> +                serial_out(up, UART_FCR, old_fcr); >> +        } >> + >>           uart_port_unlock_irqrestore(p, flags); >>       } > > -- js suse labs