On Thu, 3 Sep 2020 at 02:41, Rich Felker <dalias@xxxxxxxx> wrote: > > On Wed, Sep 02, 2020 at 05:51:16PM +0200, Geert Uytterhoeven wrote: > > Hi Rich, > > > > On Wed, Sep 2, 2020 at 5:43 PM Rich Felker <dalias@xxxxxxxx> wrote: > > > On Wed, Sep 02, 2020 at 10:31:47AM +0200, Ulf Hansson wrote: > > > > On Tue, 1 Sep 2020 at 17:40, Christoph Hellwig <hch@xxxxxx> wrote: > > > > > On Tue, Sep 01, 2020 at 05:36:17PM +0200, Ulf Hansson wrote: > > > > > > > I still don't think this makes sense, as the dma_mask should always > > > > > > > be non-NULL here. > > > > > > > > > > > > If that is the case, I wonder how the driver could even have worked without DMA. > > > > > > > > > > > > Because in the existing code, host->dma_dev gets assigned to > > > > > > spi->master->dev.parent->dma_mask - which seems to turn on the DMA > > > > > > usage in the driver. > > > > > > > > > > > > What am I missing? > > > > > > > > > > Do you know of other non-DMA users? For SH nommu it probably worked > > > > > > > > I don't know of other non-DMA users. As I said, I wish someone could > > > > step in and take better care of mmc_spi - as I know it's being used a > > > > lot. > > > > > > > > > because SH nommu used to provide a DMA implementation that worked > > > > > fine for streaming maps, but was completely broken for coherent > > > > > allocation. And this driver appears to only use the former. > > > > > > > > Alright, so you are saying the DMA support may potentially never have > > > > been optional to this driver. In any case, I can remove the check in > > > > $subject patch, as it shouldn't matter. > > > > > > DMA support was always optional, because even on systems where DMA is > > > present, it doesn't necessarily mean the SPI controller uses DMA. In > > > particular, pure bit-banged SPI via GPIOs doesn't have DMA, but has > > > always worked. See my previous reply to Christoph about host->dma_dev > > > for my current-best understanding of what's going on here. > > > > > > > Anyway, let's see what Rich thinks of this. I am curious to see if the > > > > patch works on his SH boards - as I haven't been able to test it. > > > > > > I'll rebuild and retest just to confirm, but I already tested a > > > functionally equivalent patch that just did the #ifdef inline (rather > > > than moving the logic out to separate functions) and it worked fine. > > > > Hence, Tested-by? ;-) > > Confirmed that this version of the patch works too. Thus, > > Tested-by: Rich Felker <dalias@xxxxxxxx> I have applied the patch for fixes, thanks for testing! Christoph, when it comes to the check of "spi->master->dev.parent->dma_mask", I am keeping it for now. I am simply not sure that all spi masters assign the pointer (even if most are platform drivers). I think it's better that we remove that check in a separate patch - to get it tested. Kind regards Uffe
