Re: Applied "spi: imx: dynamic burst length adjust for PIO mode" to the spi tree

From: Sascha Hauer <s.hauer@pengutronix.de>
To: Mark Brown <broonie@kernel.org>
Cc: Jiada Wang <jiada_wang@mentor.com>,
	festevam@gmail.com, linux-spi@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: Applied "spi: imx: dynamic burst length adjust for PIO mode" to the spi tree
Date: Fri, 30 Jun 2017 14:14:33 +0200	[thread overview]
Message-ID: <20170630121433.piznjqtmhy35zty6@pengutronix.de> (raw)
In-Reply-To: <E1dQub0-0008Ep-Hf@finisterre>

Hi Mark,

On Fri, Jun 30, 2017 at 01:00:22PM +0100, Mark Brown wrote:
> The patch
> 
>    spi: imx: dynamic burst length adjust for PIO mode
> 
> has been applied to the spi tree at
> 
>    git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git 

Argh, I wasn't fast enough. I just ran spi-loopback-test.ko with this
patch and it doesn't work properly.

> +	if (spi_imx->count == spi_imx->remainder) {
> +		ctrl = readl(spi_imx->base + MX51_ECSPI_CTRL);
> +		ctrl &= ~MX51_ECSPI_CTRL_BL_MASK;
> +		if (spi_imx->count > MX51_ECSPI_CTRL_MAX_BURST) {
> +			spi_imx->remainder = spi_imx->count %
> +					     MX51_ECSPI_CTRL_MAX_BURST;
> +			val = MX51_ECSPI_CTRL_MAX_BURST;

This is wrong. MX51_ECSPI_CTRL_MAX_BURST contains the burst length in
bytes, but the register 'val' is written to takes the burst length in
bits - 1, so this should be:

			val = MX51_ECSPI_CTRL_MAX_BURST * 8 - 1;

instead.

Sascha

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