linux-kernel - Re: [PATCH 1/9] spi: sunxi: fix transfer timeout

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Date:	Thu, 20 Aug 2015 16:43:07 +0200
From:	Maxime Ripard <maxime.ripard@...e-electrons.com>
To:	Michal Suchanek <hramrach@...il.com>
Cc:	linux-sunxi@...glegroups.com, Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Russell King <linux@....linux.org.uk>,
	Mark Brown <broonie@...nel.org>, devicetree@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-spi@...r.kernel.org
Subject: Re: [PATCH 1/9] spi: sunxi: fix transfer timeout

On Thu, Aug 20, 2015 at 02:19:45PM -0000, Michal Suchanek wrote:
> The trasfer timeout is fixed at 1000 ms. Reading a 4Mbyte flash over
> 1MHz SPI bus takes way longer than that. Calculate the timeout from the
> actual time the transfer is supposed to take and multiply by 2 for good
> measure.
> 
> Signed-off-by: Michal Suchanek <hramrach@...il.com>
> ---
>  drivers/spi/spi-sun4i.c | 10 +++++++++-
>  drivers/spi/spi-sun6i.c | 10 +++++++++-
>  2 files changed, 18 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/spi/spi-sun4i.c b/drivers/spi/spi-sun4i.c
> index fbb0a4d..48532ec 100644
> --- a/drivers/spi/spi-sun4i.c
> +++ b/drivers/spi/spi-sun4i.c
> @@ -170,6 +170,7 @@ static int sun4i_spi_transfer_one(struct spi_master *master,
>  {
>  	struct sun4i_spi *sspi = spi_master_get_devdata(master);
>  	unsigned int mclk_rate, div, timeout;
> +	unsigned int start, end, tx_time;
>  	unsigned int tx_len = 0;
>  	int ret = 0;
>  	u32 reg;
> @@ -279,9 +280,16 @@ static int sun4i_spi_transfer_one(struct spi_master *master,
>  	reg = sun4i_spi_read(sspi, SUN4I_CTL_REG);
>  	sun4i_spi_write(sspi, SUN4I_CTL_REG, reg | SUN4I_CTL_XCH);
>  
> +	tx_time = max_t(int, tfr->len * 8 * 2 / (speed / 1000), 100);
> +	start = jiffies;
>  	timeout = wait_for_completion_timeout(&sspi->done,
> -					      msecs_to_jiffies(1000));
> +					      msecs_to_jiffies(tx_time));
> +	end = jiffies;
>  	if (!timeout) {
> +		dev_warn(&master->dev,
> +			 "%s: timeout transferring %u bytes@...z for %i(%i)ms",
> +			 dev_name(&spi->dev), tfr->len, speed,
> +			 jiffies_to_msecs(end - start), tx_time);

Timeout already contains the number of jiffies elapsed (and I'm not
sure anyone reading that message would get that the last number is
actually the maximum timeout).

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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