Dear Simon Glass, > Hi, > > On Tue, Sep 18, 2012 at 1:04 PM, Thierry Reding > > <thierry.red...@avionic-design.de> wrote: > > On Tue, Sep 18, 2012 at 09:36:18PM +0200, Marek Vasut wrote: > >> Dear Thierry Reding, > >> > >> [...] > >> > >> > > Sure, but after you apply the bounce buffer, you can safely > >> > > invalidate the whole cacheline, so align it up and be done with it. > >> > > >> > That's what I proposed to do last time around but it was NAK'ed. > >> > >> By who? > > > > I think it was Simon Glass and Mike Frysinger. They NAK'ed it for very > > valid reason, so I'm not complaining. > > > >> > At the > >> > time I didn't ensure that the buffer was actually big enough, which is > >> > why people didn't like it (data on the stack after the DMA buffer > >> > might be invalidated as well). > >> > >> Correct, thus the bounce buffer. > > > > I don't think we even need the bounce buffer. All that needs to be done > > is guarantee that the buffers passed to the MMC driver are properly > > aligned and sized. > > > > Thierry > > Perhaps a point to make here is that we really don't want every driver > (or even driver stack) implementing bounce buffers to when it is not a > huge effort to change the code that calls them (typically filesystem > code) to do the right thing. The code will be smaller and more > efficient if the alignment issues are dealt with at source IMO.
You need the BB for user-case, when user gives you misaligned buffer. Best regards, Marek Vasut _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
