[U-Boot] [PATCH v3 10/16] drivers: mtd: spi: sf_probe: add compatible for spansion spi flash

[Tom Rini]

On Mon, Nov 23, 2015 at 04:59:12PM +0530, Mugunthan V N wrote:
> On Friday 20 November 2015 05:57 PM, Jagan Teki wrote:
> > On 20 November 2015 at 11:31, Mugunthan V N <mugunthanvnm at ti.com> wrote:
> >> Jagan
> >>
> >> On Thursday 19 November 2015 03:40 PM, Jagan Teki wrote:
> >>> On 19 November 2015 at 12:35, Mugunthan V N <mugunthanvnm at ti.com> wrote:
> >>>> Add compatible for spansion 32MiB spi flash s25fl256s1.
> >>>>
> >>>> Signed-off-by: Mugunthan V N <mugunthanvnm at ti.com>
> >>>> ---
> >>>>  drivers/mtd/spi/sf_probe.c | 1 +
> >>>>  1 file changed, 1 insertion(+)
> >>>>
> >>>> diff --git a/drivers/mtd/spi/sf_probe.c b/drivers/mtd/spi/sf_probe.c
> >>>> index bc05d30..ffbce59 100644
> >>>> --- a/drivers/mtd/spi/sf_probe.c
> >>>> +++ b/drivers/mtd/spi/sf_probe.c
> >>>> @@ -515,6 +515,7 @@ static const struct dm_spi_flash_ops spi_flash_std_ops = {
> >>>>
> >>>>  static const struct udevice_id spi_flash_std_ids[] = {
> >>>>         { .compatible = "spi-flash" },
> >>>> +       { .compatible = "s25fl256s1" },
> >>>>         { }
> >>>
> >>> Never compare with spi-flash vs s25fl256s1 here former is driver
> >>> compatible string and later one is probed flash string name. we don't
> >>> need to add them in compatible list, better to add it on dts node
> >>> otherwise no issue the connected flash will detect while 'sf probe'
> >>>
> >>
> >> I agree that spi flash will be probed even without addition of compatibles.
> >>
> >> If there is no matching compatible between the dtb and driver,  the dt
> >> properties like spi-max-frequency, spi clock phase/polarity and spi
> >> bus-width are not parsed from DT as the of_offset of the spi device will
> >> be '-1'. This check and dt parse is done in spi_child_post_bind() in
> >> spi-uclass driver.
> >>
> >> Since spi bus-width is not read from DT, by default spi transfers are
> >> done in one wire mode and read throughput drops to 5.3Mbps. With Quad
> >> mode read throughput is 16.6Mbps in DRA74x EVM.
> >>
> > 
> > Why can't we try something like this [1] [2] I do agree with
> > documentation missing, may be we add add that well.
> > 
> > [1] arch/arm/dts/socfpga_cyclone5_sockit.dts
> 
> This dts file is not in sync with kernel dts. There is no qspi support
> in kernel. It is going to be really tough time to sync this dts between
> kernel and u-boot ;)

True, but you're pushing that too, right?  I suppose the high level
take-away here is that when you're posting the bindings for Linux you
need to keep some of the U-Boot folks in CC as well.  So first up, where
/ how far along is the kernel support today?

-- 
Tom
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