On Monday, August 04, 2014 at 03:45:57 PM, Nikita Kiryanov wrote: > On 04/08/14 16:10, Marek Vasut wrote: > > 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.t...@gmail.com> > >>>> Cc: Eric Nelson <eric.nel...@boundarydevices.com> > >>>> Cc: Eric Benard <e...@eukrea.com> > >>>> Cc: Fabio Estevam <fabio.este...@freescale.com> > >>>> Cc: Tim Harvey <thar...@gateworks.com> > >>>> Cc: Stefano Babic <sba...@denx.de> > >>>> Cc: Tom Rini <tr...@ti.com> > >>>> Signed-off-by: Nikita Kiryanov <nik...@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 ? > > It's the same thing: > sf probe [[bus:]cs] [hz] [mode] > > The point is that cs 0 has to be represented as "15872", instead of "0".
That's expected, yep. > > But then, you can use CONFIG_DEFAULT_SPI_CS to specify the default CS, no > > ? > > This only works if you have just one SPI device that requires GPIO use. > Otherwise, chances are the user will have no idea how to access devices > on other chip selects without looking at the code. Oh, so you're confused by those crazy chipselect numbers ? Best regards, Marek Vasut _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
