Messages in this thread | | | Date | Wed, 23 Jan 2008 13:45:53 +0100 | From | Haavard Skinnemoen <> | Subject | Re: [PATCH 6/6] atmel_serial: Add DMA support |
| |
On Wed, 23 Jan 2008 13:30:32 +0100 Marc Pignat <marc.pignat@hevs.ch> wrote: > On Wednesday 23 January 2008, Haavard Skinnemoen wrote: > > Right. Does that mean I shouldn't Cc it on patches? > extract from the linux-arm-kernel 'Mailing List Etiquette': > 10. Cross-posting between linux-arm* lists and other lists. [[40]rmk] > Please do not do this. Subscribers on other lists may not be > subscribed to the linux-arm lists, so when they try to reply to > such a message, they will receive a bounce. This is deemed by > others to be rude behaviour on the part of the person who > originally cross-posted.
Ok, sorry about that.
> > Dunno. I suppose the PDC_BUFFER_SIZE and/or PDC_RX_TIMEOUT definitions > > needs to be revisited? Chip? > I just think there is no need to warn, even if definitions are sub-optimal.
I agree, so I replaced it with a comment.
> > I don't really understand why the buffer size depends on the cache line > > size either. Why don't we just set it to something nice and large, like > > 512 (actually 1024 since there are two buffers), and be done with it? > Probably for dma safety/performance, The PDC buffer start should be aligned to > cache line, and the size be a multiple of cache line size.
Ok, but then any power of two larger than the cache line size should be fine, assuming kmalloc() returns a properly aligned buffer.
Other than that, I can't see any reason why a platform with 64 byte cache lines should need larger buffers than one with 32 byte cache lines.
> > And while we're at it, might as well move the SUPPORT_PDC definition > > into Kconfig where it belongs... > For me there is no need to disbable pdc support once working. PDC can be > enabled/disabled in the board setup code. -> simply remove this definition.
There are still issues with the DMA code that the PIO code doesn't have. So I think it should be selectable until we can sort out the error/break handling.
Haavard -- 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/
| |