Dear Trent Piepho, > On Mon, Apr 1, 2013 at 4:37 PM, Marek Vasut <ma...@denx.de> wrote: > >> On Mon, Apr 1, 2013 at 4:16 PM, Marek Vasut <ma...@denx.de> wrote: > >> >> The ssp struct has a clock rate field, to provide the actual value, > >> >> in Hz, of the SSP output clock (the rate of SSP_SCK) after > >> >> mxs_ssp_set_clk_rate() is called. It should be read-only, except for > >> >> mxs_ssp_set_clk_rate(). > >> >> > >> >> For some reason the spi-mxs driver decides to write to this field on > >> >> init, and sets it to the value of the SSP input clock (clk_sspN, from > >> >> the MXS clocking block) in kHz. It shouldn't be setting the value, > >> >> and certainly shouldn't be setting it with the wrong clock in the > >> >> wrong units. > >> > > >> > I suspect this patch should also fix drivers/clk/mxs/clk-ssp.c then? > >> > >> Why do you say that? I see no problem with clk-ssp.c, as setting the > >> clk_rate field in the ssp struct to the actual programmed rate makes > >> sense. The code in spi-mxs.c just makes no sense. I suspect it was > >> added by mistake when porting the driver. > > > > Either remove it altogether if it's unused OR make sure it's inited to > > some sane value from the start. > > This field doesn't need to be initted by a user of the common SSP > clock code, as it is not an input to that code. It is set by the SSP > clock code. After the SSP clock is programmed, it can be read to find > the true SSP rate. There is no need for any user of the SSP code to > set the clk_rate field, and other than this one incorrect line, no > user does so. It's not used currently in the SPI driver at all, but > it certainly could be. The SSP code is shared with the MMC driver > that can drive an SSP port in SD/MMC mode. The mxs-mmc code does need > the actual SSP clock and does use the field. That code does not write > to ssp->clk_rate, because as I have said, it is in output from the SSP > clock code.
If the clk_rate is at least inited to zero, then this patch does makes sense. [...] Best regards, Marek Vasut ------------------------------------------------------------------------------ Own the Future-Intel(R) Level Up Game Demo Contest 2013 Rise to greatness in Intel's independent game demo contest. Compete for recognition, cash, and the chance to get your game on Steam. $5K grand prize plus 10 genre and skill prizes. Submit your demo by 6/6/13. http://altfarm.mediaplex.com/ad/ck/12124-176961-30367-2 _______________________________________________ spi-devel-general mailing list spi-devel-general@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/spi-devel-general
