linux-kernel - Re: [PATCHv2] drivers: spi: Add qspi flash controller

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Date:	Tue, 2 Jul 2013 13:43:38 +0300
From:	Felipe Balbi <balbi@...com>
To:	Mark Brown <broonie@...nel.org>
CC:	Felipe Balbi <balbi@...com>, Sourav Poddar <sourav.poddar@...com>,
	<spi-devel-general@...ts.sourceforge.net>,
	<grant.likely@...aro.org>, <rnayak@...com>,
	<linux-omap@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCHv2] drivers: spi: Add qspi flash controller

On Tue, Jul 02, 2013 at 11:17:18AM +0100, Mark Brown wrote:
> On Tue, Jul 02, 2013 at 12:44:04PM +0300, Felipe Balbi wrote:
> > On Tue, Jul 02, 2013 at 10:32:47AM +0100, Mark Brown wrote:
> 
> > > Does this hardware really support anything other than 8 bits per word?
> > > There is no code in the driver which pays any attention to the word
> > > size...
> 
> > the HW has a 128-bit shift register ;-) but driver doesn't look
> > complete.
> 
> That's not the issue - remember that SPI specifies big endian byte
> ordering for words on the bus so things will need to be reordered by the
> hardware for anything except 8 bits.

right, the driver is far from being complete. In fact this driver is
quite buggy, if you look here :

> +static int dra7xxx_qspi_start_transfer_one(struct spi_master *master,
> +		struct spi_message *m)
> +{
> +	struct dra7xxx_qspi *qspi = spi_master_get_devdata(master);
> +	struct spi_device *spi = m->spi;
> +	struct spi_transfer *t;
> +	int status = 0;
> +	int flags = 0;
> +
> +	/* setup command reg */
> +	qspi->cmd = 0;
> +	qspi->cmd |= QSPI_WLEN(8);

Sourav hardcodes wordlenght to 8-bits, and yet he enables 8, 16 and
32-bits per word.

> +	qspi->cmd |= QSPI_EN_CS(0);

he's also hardcoding the chipselect line which should be take from
m->spi->chip_select

> +	qspi->cmd |= 0xfff;

and he's hardcoding the frame length to 4096 frames!!

This is all buggy.

-- 
balbi

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