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 2E9911B87D5; Tue, 6 May 2025 07:32:24 +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=1746516745; cv=none; b=FW+QBOkdtwVSUFwqm4VPCwREDv3FkWBAQ8het/lud99fdF2zLTtRTeueA0ss4IX2XJdlKhemkWBMU9/pSs191TCIWVaES0qsLYHOLtRNcTZr58i8AiikIRFOScn/GBb9lZeAmFZln1r1WZy7UAoJwIjip1+vFSX2EeLxjU94yS0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746516745; c=relaxed/simple; bh=OZ+817j3f4ap3ciSYtXNhpzUyN6ZWEuAU+9/pHf4lCM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=kCe3WAQMtJrvpQ1XGkWGyXRGpel+KKevyKpsaFjDB4uJDwx0xkV2LV6aV5nPBDP3fp9Iu/hXjWnoZYIxsLaISsrg3T9X1cAOeu6314FVrDohBVqyYC3zvyjitHj1pRxUujfBv3Pd5mWVQrhC9GdzqVYDC/5z2jWPaWiZmTjXkD4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KXEQhvyA; 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="KXEQhvyA" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B9C97C4CEEB; Tue, 6 May 2025 07:32:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1746516744; bh=OZ+817j3f4ap3ciSYtXNhpzUyN6ZWEuAU+9/pHf4lCM=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=KXEQhvyAE6H3yr0cAjm0ZCd8bzQU5YeUOhzY6VnpxRnZEd6cGYABBJ6+3fV+E17Va ZBol3J9puJE1Azne5e0tMYVmqBBHgeC19U8udesyzs8pxwXSVUFkOWWayuUTG6uW8a hsSxVQSn48DHLODGZ53Ha+0Y7cTEpVXEnFd/8J7IudC5RnevLPhUhy6K1luIDOj+xn ZYLHtgVPAYWXREWQAPhvrgB6g80YOH8gxEni8mDkf81wXjWBTVHfebM5GqFlIIZZC/ 2yAeeF6lOegaFwQnNLQ9j8EAAsv9lm5Z1w9DTJFNnQb1TauXVS2CnWwqm0gN52IgWQ Q+mHkoLCAIbJg== Message-ID: <7a814f93-49b5-4b62-ae2c-dc28f174b11a@kernel.org> Date: Tue, 6 May 2025 09:32:21 +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] tty: serial: 8250_omap: fix tx with dma To: Mans Rullgard , Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org References: <20250430163709.15850-1-mans@mansr.com> Content-Language: en-US From: Jiri Slaby Autocrypt: addr=jirislaby@kernel.org; keydata= xsFNBE6S54YBEACzzjLwDUbU5elY4GTg/NdotjA0jyyJtYI86wdKraekbNE0bC4zV+ryvH4j rrcDwGs6tFVrAHvdHeIdI07s1iIx5R/ndcHwt4fvI8CL5PzPmn5J+h0WERR5rFprRh6axhOk rSD5CwQl19fm4AJCS6A9GJtOoiLpWn2/IbogPc71jQVrupZYYx51rAaHZ0D2KYK/uhfc6neJ i0WqPlbtIlIrpvWxckucNu6ZwXjFY0f3qIRg3Vqh5QxPkojGsq9tXVFVLEkSVz6FoqCHrUTx wr+aw6qqQVgvT/McQtsI0S66uIkQjzPUrgAEtWUv76rM4ekqL9stHyvTGw0Fjsualwb0Gwdx ReTZzMgheAyoy/umIOKrSEpWouVoBt5FFSZUyjuDdlPPYyPav+hpI6ggmCTld3u2hyiHji2H cDpcLM2LMhlHBipu80s9anNeZhCANDhbC5E+NZmuwgzHBcan8WC7xsPXPaiZSIm7TKaVoOcL 9tE5aN3jQmIlrT7ZUX52Ff/hSdx/JKDP3YMNtt4B0cH6ejIjtqTd+Ge8sSttsnNM0CQUkXps w98jwz+Lxw/bKMr3NSnnFpUZaxwji3BC9vYyxKMAwNelBCHEgS/OAa3EJoTfuYOK6wT6nadm YqYjwYbZE5V/SwzMbpWu7Jwlvuwyfo5mh7w5iMfnZE+vHFwp/wARAQABzSFKaXJpIFNsYWJ5 IDxqaXJpc2xhYnlAa2VybmVsLm9yZz7CwXcEEwEIACEFAlW3RUwCGwMFCwkIBwIGFQgJCgsC BBYCAwECHgECF4AACgkQvSWxBAa0cEnVTg//TQpdIAr8Tn0VAeUjdVIH9XCFw+cPSU+zMSCH eCZoA/N6gitEcnvHoFVVM7b3hK2HgoFUNbmYC0RdcSc80pOF5gCnACSP9XWHGWzeKCARRcQR 4s5YD8I4VV5hqXcKo2DFAtIOVbHDW+0okOzcecdasCakUTr7s2fXz97uuoc2gIBB7bmHUGAH XQXHvdnCLjDjR+eJN+zrtbqZKYSfj89s/ZHn5Slug6w8qOPT1sVNGG+eWPlc5s7XYhT9z66E l5C0rG35JE4PhC+tl7BaE5IwjJlBMHf/cMJxNHAYoQ1hWQCKOfMDQ6bsEr++kGUCbHkrEFwD UVA72iLnnnlZCMevwE4hc0zVhseWhPc/KMYObU1sDGqaCesRLkE3tiE7X2cikmj/qH0CoMWe gjnwnQ2qVJcaPSzJ4QITvchEQ+tbuVAyvn9H+9MkdT7b7b2OaqYsUP8rn/2k1Td5zknUz7iF oJ0Z9wPTl6tDfF8phaMIPISYrhceVOIoL+rWfaikhBulZTIT5ihieY9nQOw6vhOfWkYvv0Dl o4GRnb2ybPQpfEs7WtetOsUgiUbfljTgILFw3CsPW8JESOGQc0Pv8ieznIighqPPFz9g+zSu Ss/rpcsqag5n9rQp/H3WW5zKUpeYcKGaPDp/vSUovMcjp8USIhzBBrmI7UWAtuedG9prjqfO wU0ETpLnhgEQAM+cDWLL+Wvc9cLhA2OXZ/gMmu7NbYKjfth1UyOuBd5emIO+d4RfFM02XFTI t4MxwhAryhsKQQcA4iQNldkbyeviYrPKWjLTjRXT5cD2lpWzr+Jx7mX7InV5JOz1Qq+P+nJW YIBjUKhI03ux89p58CYil24Zpyn2F5cX7U+inY8lJIBwLPBnc9Z0An/DVnUOD+0wIcYVnZAK DiIXODkGqTg3fhZwbbi+KAhtHPFM2fGw2VTUf62IHzV+eBSnamzPOBc1XsJYKRo3FHNeLuS8 f4wUe7bWb9O66PPFK/RkeqNX6akkFBf9VfrZ1rTEKAyJ2uqf1EI1olYnENk4+00IBa+BavGQ 8UW9dGW3nbPrfuOV5UUvbnsSQwj67pSdrBQqilr5N/5H9z7VCDQ0dhuJNtvDSlTf2iUFBqgk 3smln31PUYiVPrMP0V4ja0i9qtO/TB01rTfTyXTRtqz53qO5dGsYiliJO5aUmh8swVpotgK4 /57h3zGsaXO9PGgnnAdqeKVITaFTLY1ISg+Ptb4KoliiOjrBMmQUSJVtkUXMrCMCeuPDGHo7 39Xc75lcHlGuM3yEB//htKjyprbLeLf1y4xPyTeeF5zg/0ztRZNKZicgEmxyUNBHHnBKHQxz 1j+mzH0HjZZtXjGu2KLJ18G07q0fpz2ZPk2D53Ww39VNI/J9ABEBAAHCwV8EGAECAAkFAk6S 54YCGwwACgkQvSWxBAa0cEk3tRAAgO+DFpbyIa4RlnfpcW17AfnpZi9VR5+zr496n2jH/1ld wRO/S+QNSA8qdABqMb9WI4BNaoANgcg0AS429Mq0taaWKkAjkkGAT7mD1Q5PiLr06Y/+Kzdr 90eUVneqM2TUQQbK+Kh7JwmGVrRGNqQrDk+gRNvKnGwFNeTkTKtJ0P8jYd7P1gZb9Fwj9YLx jhn/sVIhNmEBLBoI7PL+9fbILqJPHgAwW35rpnq4f/EYTykbk1sa13Tav6btJ+4QOgbcezWI wZ5w/JVfEJW9JXp3BFAVzRQ5nVrrLDAJZ8Y5ioWcm99JtSIIxXxt9FJaGc1Bgsi5K/+dyTKL wLMJgiBzbVx8G+fCJJ9YtlNOPWhbKPlrQ8+AY52Aagi9WNhe6XfJdh5g6ptiOILm330mkR4g W6nEgZVyIyTq3ekOuruftWL99qpP5zi+eNrMmLRQx9iecDNgFr342R9bTDlb1TLuRb+/tJ98 f/bIWIr0cqQmqQ33FgRhrG1+Xml6UXyJ2jExmlO8JljuOGeXYh6ZkIEyzqzffzBLXZCujlYQ DFXpyMNVJ2ZwPmX2mWEoYuaBU0JN7wM+/zWgOf2zRwhEuD3A2cO2PxoiIfyUEfB9SSmffaK/ S4xXoB6wvGENZ85Hg37C7WDNdaAt6Xh2uQIly5grkgvWppkNy4ZHxE+jeNsU7tg= In-Reply-To: <20250430163709.15850-1-mans@mansr.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 30. 04. 25, 18:37, Mans Rullgard wrote: > Commit 1788cf6a91d9 ("tty: serial: switch from circ_buf to kfifo") > introduced two errors in the TX DMA handling for 8250_omap. > > Firstly, kfifo_dma_out_prepare_mapped() needs a scatterlist with two > entries whereas only one is provided. The same error was fixed for > 8250_dma in 59449c9dbdaa ("tty: serial: 8250_dma: use sgl with 2 nents > to take care of buffer wrap"). It's not an error. This is how it used to work since ever. Providing two is an optimization, right? > Secondly, when the OMAP_DMA_TX_KICK flag is set, one byte is pulled from > the kfifo and emitted directly in order to start the DMA. > This is done without updating DMA tx_size Ah, that's an error, of course. > which leads to uart_xmit_advance() called > in the DMA complete callback advancing the kfifo by one too much. > > In practice, transmitting N bytes has been seen to result in the last > N-1 bytes being sent repeatedly. > > This change fixes both problems. I am not sure you want to mix fixups with features. > Fixes: 1788cf6a91d9 ("tty: serial: switch from circ_buf to kfifo") > Signed-off-by: Mans Rullgard ... > @@ -1248,8 +1247,10 @@ static int omap_8250_tx_dma(struct uart_8250_port *p) > err: > dma->tx_err = 1; > out_skip: > - if (skip_byte >= 0) > + if (skip_byte >= 0) { > serial_out(p, UART_TX, skip_byte); > + p->port.icount.tx++; This is unrelated (but correct) too. thanks, -- js suse labs