From: Arnd Bergmann <arnd@arndb.de>
To: linux-arm-kernel@lists.infradead.org
Cc: Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
gregkh@linuxfoundation.org, jslaby@suse.com, baohua@kernel.org,
kernel-janitors@vger.kernel.org, linux-serial@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] serial: sirf: Simplify a test
Date: Mon, 07 Nov 2016 14:50:27 +0100 [thread overview]
Message-ID: <2916662.De1FDumaQl@wuerfel> (raw)
In-Reply-To: <20161101070333.12255-1-christophe.jaillet@wanadoo.fr>
On Tuesday, November 1, 2016 8:03:33 AM CET Christophe JAILLET wrote:
> 'dmaengine_prep_dma_cyclic()' does not return an error pointer, so the test
> can be simplified to be more consistent.
>
> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
The change looks correct in principle. It would be good to automate looking
for other instances of this bug. How did you find it? Do you have e.g. a
coccinelle script or did you just stumble over the issue by accident?
There is one problem with your patch:
> drivers/tty/serial/sirfsoc_uart.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/tty/serial/sirfsoc_uart.c b/drivers/tty/serial/sirfsoc_uart.c
> index b186c9c4f850..666ca3156961 100644
> --- a/drivers/tty/serial/sirfsoc_uart.c
> +++ b/drivers/tty/serial/sirfsoc_uart.c
> @@ -609,7 +609,7 @@ static void sirfsoc_uart_start_next_rx_dma(struct uart_port *port)
> sirfport->rx_dma_items.dma_addr, SIRFSOC_RX_DMA_BUF_SIZE,
> SIRFSOC_RX_DMA_BUF_SIZE / 2,
> DMA_DEV_TO_MEM, DMA_PREP_INTERRUPT);
> - if (IS_ERR_OR_NULL(sirfport->rx_dma_items.desc)) {
> + if (!sirfport->rx_dma_items.desc) {
> dev_err(port->dev, "DMA slave single fail\n");
> return;
> }
The serial driver is for the sirf platform, which uses the sirf-dma
dmaengine driver, and that particular driver has an incorrect
dma_prep_cyclic implementation, so I think we also need this fix:
diff --git a/drivers/dma/sirf-dma.c b/drivers/dma/sirf-dma.c
index 8f62edad51be..220c611c89ae 100644
--- a/drivers/dma/sirf-dma.c
+++ b/drivers/dma/sirf-dma.c
@@ -775,7 +775,7 @@ sirfsoc_dma_prep_cyclic(struct dma_chan *chan, dma_addr_t addr,
* BUFB
*/
if (buf_len != 2 * period_len)
- return ERR_PTR(-EINVAL);
+ return NULL;
/* Get free descriptor */
spin_lock_irqsave(&schan->lock, iflags);
Arnd
next prev parent reply other threads:[~2016-11-07 13:51 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-01 7:03 [PATCH] serial: sirf: Simplify a test Christophe JAILLET
2016-11-07 13:50 ` Arnd Bergmann [this message]
2016-11-07 17:19 ` Julia Lawall
2016-11-08 7:18 ` Christophe JAILLET
2016-11-08 11:41 ` Arnd Bergmann
2016-11-10 21:18 ` Julia Lawall
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