Dear Simon Glass, > Hi, > > On Tue, Sep 18, 2012 at 2:21 PM, Marek Vasut <ma...@denx.de> wrote: > > 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. > > Yes, although I think you are talking about non-filesystem (i.e. raw)
Like fatload ? Fatload doesn't use any interim buffer either, so not only raw. > access, and it would be odd to read a kernel to a non-cached-aligned > address. If we want to support that, we can (perhaps even in the > command itself)., but at least U-Boot's own code should ideally not > generate unaligned access. Correct > > Regards, > Simon > > > Best regards, > > Marek Vasut Best regards, Marek Vasut _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
