[U-Boot] [PATCH v2] spi: omap3: Fix timeout handling

[Jagan Teki]

On 24 April 2015 at 17:04, D. Dueck <davidcdueck at googlemail.com> wrote:
> As requested:
> Tested-by: David Dueck <davidcdueck at googlemail.com>
>
>
> Am Freitag, 24. April 2015 schrieb Jagan Teki :
>>
>> On 7 April 2015 at 05:55, Tom Rini <trini at konsulko.com> wrote:
>> > On Wed, Apr 01, 2015 at 04:21:50PM +0100, Andy Pont wrote:
>> >> Hi David,
>> >>
>> >> <snipped for brevity>
>> >>
>> >> >     for (i = 0; i < len; i++) {
>> >> >             /* wait till TX register is empty (TXS == 1) */
>> >> > +           start = get_timer(0);
>> >> >             while (!(readl(&ds->regs->channel[ds->slave.cs].chstat) &
>> >> >                      OMAP3_MCSPI_CHSTAT_TXS)) {
>> >> > -                   if (--timeout <= 0) {
>> >> > +                   if (get_timer(start) > SPI_WAIT_TIMEOUT) {
>> >> >                             printf("SPI TXS timed out,
>> >> > status=0x%08x\n",
>> >> >                                    readl(&ds->regs->channel[ds-
>> >> > >slave.cs].chstat));
>> >> >                             return -1;
>> >>
>> >> I have a couple of questions...
>> >>
>> >> Firstly, when in SPL is there access to the get_timer() function?
>> >
>> > We call timer_init() from board_init_r() in SPL, prior to diving down
>> > into loading (or checking for Falcon vs Regular) so this is safe.
>> >
>> >> Secondly, when using Falcon mode to load Linux directly from SPI
>> >> (Falcon
>> >> mode) then we want to maximise the throughput and save every CPU cycle
>> >> we
>> >> possibly can.  Adding yet another function call into the for loop and
>> >> hence
>> >> calling it a couple of million times seems, on the face of it, like it
>> >> is
>> >> going to slow things down.
>> >
>> > I'd like to see measurements to prove me wrong but this both seems like
>> > a bad idea (optimizing by being incorrect, this gives us a correct
>> > timeout check like other drivers do) and really unlikely I would think
>> > to be noticable.  Since we'll be doing the same code-paths in both
>> > regular and SPL, trying to time things (by loading a big file) would be
>> > easy enough I think.  Thanks!
>>
>> Ping

Applied to u-boot-spi/master

thanks!
-- 
Jagan.