Vinod Koul <vinod.koul@xxxxxxxxx> writes: > On Tue, Feb 09, 2016 at 08:20:05AM +0100, Robert Jarzmik wrote: >> Vinod Koul <vinod.koul@xxxxxxxxx> writes: >> >> > On Mon, Feb 08, 2016 at 03:18:51PM +0100, Robert Jarzmik wrote: >> >> The current number of requestor lines is limited to 31. This was an >> >> error of a previous commit, as this number is platform dependent, and is >> >> actually : >> >> - for pxa25x: 40 requestor lines >> >> - for pxa27x: 74 requestor lines >> >> - for pxa3xx: 100 requestor lines >> >> >> >> As the driver doesn't need to know the exact number, but only an >> > >> > and why would that be a good assumption? >> Well, the driver doesn't use the exact value. Would that be 128, 1000 or 10000, >> it wouldn't change its behavior. The clients either pass -1UL (ie. no flow >> control) or a requestor line number. > > Somehow that does not sound right to me. You seem to have no way of knowing > what is the actual max request line for a platforms. What if on pxa25x user > requests more than 40 lines? > >> > Btw shouldn't this data come from DT? >> It can if you wish, but in this case I must amend the platform data case too, ie >> mmp_dma_platdata. And this has an impact on MMP architecture. I'd rather have >> the simpler approach unless you really want the exact number of requestor lines >> to be passed in platform_data+DT. > > The information that you have X lines on a platform needs to be described > and queried. I see current approach error prone Actually I have thought over your point, and you're quite right (this is your case of more than 40 lines). The exception I have found is : - a device driver is wrongly written - it requests the requestor line 0x1000 (below 0x8000) - pxa_dma computes the register in pxad_drcmr(0x1000) => this gives : base + 0x1000 + 4 * 0x1000 = base + 0x5000 => this is a not existing iomapped register So yes, I will respin the patchset, with : - one patch adding the number of requestors in mmp_dma.h - one patch adding the number of requestors in devicetree description - one patch adding the number of requestors in arch/arm/mach-pxa (my tree) - one patch adding the use of number of requestors in pxa_dma.c Cheers. -- Robert -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
