From: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
To: Tamseel Shams <m.shams@samsung.com>,
gregkh@linuxfoundation.org, jirislaby@kernel.org
Cc: linux-arm-kernel@lists.infradead.org,
linux-samsung-soc@vger.kernel.org, linux-serial@vger.kernel.org,
linux-kernel@vger.kernel.org, alim.akhtar@samsung.com,
ajaykumar.rs@samsung.com, robin.murphy@arm.com
Subject: Re: [PATCH v4] serial: samsung: use dma_ops of DMA if attached
Date: Mon, 28 Jun 2021 10:44:51 +0200 [thread overview]
Message-ID: <3aa88ee4-c662-8069-fb04-90df82038dbe@canonical.com> (raw)
In-Reply-To: <20210625075114.71155-1-m.shams@samsung.com>
On 25/06/2021 09:51, Tamseel Shams wrote:
> When DMA is used for TX and RX by serial driver, it should
> pass the DMA device pointer to DMA API instead of UART device
> pointer. DMA device should be used for DMA API because only
> the DMA device is aware of how the device connects to the memory.
> There might be an extra level of address translation due to a
> SMMU attached to the DMA device. When serial device is used for
> DMA API, the DMA API will have no clue of the SMMU attached to
> the DMA device.
>
> This patch is necessary to fix the SMMU page faults
> which is observed when a DMA(with SMMU enabled) is attached
> to UART for transfer.
>
> Signed-off-by: Tamseel Shams <m.shams@samsung.com>
> Signed-off-by: Ajay Kumar <ajaykumar.rs@samsung.com>
> ---
> Changes since v1:
> 1. Rebased the patch on "tty-next" branch of TTY driver tree
>
> Changes since v2:
> 1. Updated the commit message.
> 2. Changed the comment description
>
> Changes since v3:
> 1. Removed the null pointer check for "dma", "dma->tx_chan" and
> "dma->rx_chan" and instead sending DMA device pointer while calling
> DMA API.
>
> drivers/tty/serial/samsung_tty.c | 32 ++++++++++++++++----------------
> 1 file changed, 16 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c
> index 9fbc61151c2e..fa30aa20a13f 100644
> --- a/drivers/tty/serial/samsung_tty.c
> +++ b/drivers/tty/serial/samsung_tty.c
> @@ -305,7 +305,7 @@ static void s3c24xx_serial_stop_tx(struct uart_port *port)
> dmaengine_pause(dma->tx_chan);
> dmaengine_tx_status(dma->tx_chan, dma->tx_cookie, &state);
> dmaengine_terminate_all(dma->tx_chan);
> - dma_sync_single_for_cpu(ourport->port.dev,
> + dma_sync_single_for_cpu(dma->tx_chan->device->dev,
> dma->tx_transfer_addr, dma->tx_size, DMA_TO_DEVICE);
> async_tx_ack(dma->tx_desc);
> count = dma->tx_bytes_requested - state.residue;
> @@ -338,8 +338,8 @@ static void s3c24xx_serial_tx_dma_complete(void *args)
> count = dma->tx_bytes_requested - state.residue;
> async_tx_ack(dma->tx_desc);
>
> - dma_sync_single_for_cpu(ourport->port.dev, dma->tx_transfer_addr,
> - dma->tx_size, DMA_TO_DEVICE);
> + dma_sync_single_for_cpu(dma->tx_chan->device->dev,
> + dma->tx_transfer_addr, dma->tx_size, DMA_TO_DEVICE);
Looks like alignment is broken here. However even if the line was not
aligned before, please fix it up now - align the arguments like
checkpatch suggests.
This applies to other places as well. Thanks.
Best regards,
Krzysztof
next prev parent reply other threads:[~2021-06-28 8:45 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20210625074751epcas5p125067e47c4ff1ad24a1e595d85f82540@epcas5p1.samsung.com>
2021-06-25 7:51 ` [PATCH v4] serial: samsung: use dma_ops of DMA if attached Tamseel Shams
2021-06-28 8:44 ` Krzysztof Kozlowski [this message]
2021-06-28 13:37 ` M Tamseel Shams
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=3aa88ee4-c662-8069-fb04-90df82038dbe@canonical.com \
--to=krzysztof.kozlowski@canonical.com \
--cc=ajaykumar.rs@samsung.com \
--cc=alim.akhtar@samsung.com \
--cc=gregkh@linuxfoundation.org \
--cc=jirislaby@kernel.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-samsung-soc@vger.kernel.org \
--cc=linux-serial@vger.kernel.org \
--cc=m.shams@samsung.com \
--cc=robin.murphy@arm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).