linux-kernel - Re: [PATCH 7/8] spi: sun6i: use 'time_left' variable with wait_for_completion

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Message-ID: <20240429131600.4e910d8a@donnerap.manchester.arm.com>
Date: Mon, 29 Apr 2024 13:16:00 +0100
From: Andre Przywara <andre.przywara@....com>
To: Wolfram Sang <wsa+renesas@...g-engineering.com>
Cc: linux-spi@...r.kernel.org, Mark Brown <broonie@...nel.org>, Chen-Yu Tsai
 <wens@...e.org>, Jernej Skrabec <jernej.skrabec@...il.com>, Samuel Holland
 <samuel@...lland.org>, linux-arm-kernel@...ts.infradead.org,
 linux-sunxi@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 7/8] spi: sun6i: use 'time_left' variable with
 wait_for_completion_timeout()

On Mon, 29 Apr 2024 13:28:40 +0200
Wolfram Sang <wsa+renesas@...g-engineering.com> wrote:

Hi,

> There is a confusing pattern in the kernel to use a variable named 'timeout' to
> store the result of wait_for_completion_timeout() causing patterns like:
> 
> 	timeout = wait_for_completion_timeout(...)
> 	if (!timeout) return -ETIMEDOUT;
> 
> with all kinds of permutations. Use 'time_left' as a variable to make the code
> self explaining.
> 
> Fix to the proper variable type 'unsigned long' while here.
> 
> Signed-off-by: Wolfram Sang <wsa+renesas@...g-engineering.com>
> ---
>  drivers/spi/spi-sun6i.c | 17 +++++++++--------
>  1 file changed, 9 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/spi/spi-sun6i.c b/drivers/spi/spi-sun6i.c
> index cd018ea1abf1..7bbe7ea0d66a 100644
> --- a/drivers/spi/spi-sun6i.c
> +++ b/drivers/spi/spi-sun6i.c
> @@ -277,7 +277,8 @@ static int sun6i_spi_transfer_one(struct spi_controller *host,
>  				  struct spi_transfer *tfr)
>  {
>  	struct sun6i_spi *sspi = spi_controller_get_devdata(host);
> -	unsigned int div, div_cdr1, div_cdr2, timeout;
> +	unsigned int div, div_cdr1, div_cdr2;
> +	unsigned long time_left;
>  	unsigned int start, end, tx_time;
>  	unsigned int trig_level;
>  	unsigned int tx_len = 0, rx_len = 0, nbits = 0;
> @@ -488,26 +489,26 @@ static int sun6i_spi_transfer_one(struct spi_controller *host,
>  
>  	tx_time = spi_controller_xfer_timeout(host, tfr);
>  	start = jiffies;
> -	timeout = wait_for_completion_timeout(&sspi->done,
> -					      msecs_to_jiffies(tx_time));
> +	time_left = wait_for_completion_timeout(&sspi->done,
> +						msecs_to_jiffies(tx_time));
>  
>  	if (!use_dma) {
>  		sun6i_spi_drain_fifo(sspi);
>  	} else {
> -		if (timeout && rx_len) {
> +		if (time_left && rx_len) {
>  			/*
>  			 * Even though RX on the peripheral side has finished
>  			 * RX DMA might still be in flight
>  			 */
> -			timeout = wait_for_completion_timeout(&sspi->dma_rx_done,
> -							      timeout);
> -			if (!timeout)
> +			time_left = wait_for_completion_timeout(&sspi->dma_rx_done,
> +							      time_left);

Nit: indentation is off here. Regardless:

Reviewed-by: Andre Przywara <andre.przywara@....com>

Cheers,
Andre

> +			if (!time_left)
>  				dev_warn(&host->dev, "RX DMA timeout\n");
>  		}
>  	}
>  
>  	end = jiffies;
> -	if (!timeout) {
> +	if (!time_left) {
>  		dev_warn(&host->dev,
>  			 "%s: timeout transferring %u bytes@...z for %i(%i)ms",
>  			 dev_name(&spi->dev), tfr->len, tfr->speed_hz,