Messages in this thread | | | Subject | Re: [PATCH 09/14] Blackfin SPI driver: Fix SPI driver to work with SPI flash ST25P16 on bf548 | From | Bryan Wu <> | Date | Wed, 31 Oct 2007 14:50:31 +0800 |
| |
On Tue, 2007-10-30 at 13:05 -0700, David Brownell wrote: > On Tuesday 30 October 2007, Bryan Wu wrote: > > Current SPI driver enables SPI controller and set the SPI baud register > > for each SPI transfer. But, they should never be changed within a SPI > > message session, in which seveal SPI transfers are pumped. > > That's actually not true. If a driver sets spi_transfer.max_speed_hz > to a nonzero value that's different from the previous bit rate (which > may be spi_device.max_speed_hz), it should be updated before that > transfer segment. Example, sometimes data can't be clocked out at > the same rate commands can be clocked in. > > Similarly with spi_transfer.bits_per_word ... again, it's very possible > that commands and data have different sizes. > I agree with you here.
Maybe there are some confusion of mixing up the spi_trasnfer.speed_hz with the spi_device.max_speed_hz.
spi_device.max_speed_hz comes from spi_board_info.max_speed_hz, it is for the default max speed value. spi_transfer.speed_hz comes from upper applications for each spi transfer setting.
Am I right?
I will fix this later.
> Of course, if those values don't change, there'd be no point in > reconfiguring any aspect of those communications parameters... > > > I'll be forwarding this patch, since this looks like another case > where the main effect of the patch doesn't match its description > and since this patch series has taken too long already. (Does this > patch even really relate primarily to working with an ST M25P16 > flash part??) Though it'd be reasonable to be more hard-nosed > about this and insist on another go-around for thesse patches. > (Making this the fifth one??) > > But I *STRONGLY* suggest someone revisit the issue of whether those > two per-transfer options are now being handled correctly. As well > as update procedures so that the patch comments start to have a > direct correspondence to what the patches have changed... >
OK, we will test this on our hardware. Thanks, Dave -Bryan Wu - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |