[U-Boot] [PATCH 03/18] sf: fix sf probe

[Marek Vasut]

On Monday, August 04, 2014 at 02:48:54 PM, Nikita Kiryanov wrote:
> Hi Marek,
> 
> On 03/08/14 16:46, Marek Vasut wrote:
> > On Sunday, August 03, 2014 at 09:34:33 AM, Nikita Kiryanov wrote:
> >> MXC SPI driver has a feature whereas a GPIO line can be used as a CS
> >> signal. This is set up by joining the CS and GPIO values into a single
> >> value using (cs | gpio << 8), and passing it off as a CS value. This
> >> breaks the sf probe command, because it is no longer possible to invoke
> >> it as sf probe <cs>. Instead, the user must use sf probe <cs | gpio <<
> >> 8>.
> >> 
> >> Fix this by introducing a new board function: board_spi_cs_gpio().
> >> When called, board_spi_cs_gpio() will return the gpio number for the
> >> cs value it is given.
> >> 
> >> Cc: Jagannadha Sutradharudu Teki <jagannadh.teki at gmail.com>
> >> Cc: Eric Nelson <eric.nelson at boundarydevices.com>
> >> Cc: Eric Benard <eric at eukrea.com>
> >> Cc: Fabio Estevam <fabio.estevam at freescale.com>
> >> Cc: Tim Harvey <tharvey at gateworks.com>
> >> Cc: Stefano Babic <sbabic at denx.de>
> >> Cc: Tom Rini <trini at ti.com>
> >> Signed-off-by: Nikita Kiryanov <nikita at compulab.co.il>
> > 
> > Just curious, but is this fixing generic SF code or MXC SPI driver ? I'd
> > think the later, but it's not obvious from neither the description nor
> > the subject. I don't quite understand the problem that you're trying to
> > fix either, what happened, did the user command interface change ?
> 
> The U-Boot shell command "sf probe" can accept a chip select value, but
> if the SPI device on the other end requires an active chip-select over
> multiple transactions (achieved in the MXC SPI driver using a GPIO),
> simply typing something like "sf probe 0" will not work.

Why not ?

> This is because whatever the user passes as chip select is propagated
> to the driver, and the driver expects this value to have GPIO
> information. So for example, if IMX_GPIO_NR(2, 30) is used to force
> active chip select 0, then instead of "sf probe 0" the user will have
> to type "sf probe 15872".

You mean sf probe 0:15872 , right ? But then, you can use CONFIG_DEFAULT_SPI_CS 
to specify the default CS, no ?

> I agree that the subject line should be made a bit more specific
> to mxc_spi though...
> 
> > [...]
> > Best regards,
> > Marek Vasut

Best regards,
Marek Vasut