Re: [PATCH 2/3] MUSB : Fix for DaVinci CPPI DMA incorrect handling of actual_len field

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Hello.

Felipe Balbi wrote:

... but that implies a substantial cleanup of the DMA paths,
and I'll be content to defer such only-one-place cleanup until
that happens.

for sure today's code is really messy. All those ifs and ifdefery to
check which dma we're using look awful...
To summarize, musb_hdrc has four basic DMA paths today, the
cross product of {RX, TX} and {host, gadget}, each of which
looks more or less like

	if (cppi/davinci)
		do this
	else if (omap native/TUSB)
		do that
	else if (mentor's DMA)
		do something else

... I'm trying to move that to something like:

if (use_dma)
	do_this();
else
	do_pio();

I'm also not sure it's a good idea to handle DMA compeltion by calling musb_host_[rt]x() -- IMHO, having a separate DMA completion handling functions would lead to a cleaner code...

So that it would be, on musb side, all be running the same code and the
dma-specific code should handle the peculiarities of itself. It's been a
hard work clean up all that code and so far I'm testing only on mentor
graphics dma, when I get mentor fully working with mode i'll check
tusb6010 and later davinci with cppi.

CPPI basically fails now with the bulk transfers, at least under the high load -- the patch is coming... I don't feel sure but looking at the Inventra DMA code it seems that it might have the same issue when using DMA mode 1 -- I don't see where it clears TXCSR.DMAReqMode bit if it decides to set TxPktRdy instead of calling musb_dma_completion(), so it should never be getting another interrupt on TxPktRdy = 0...

WBR, Sergei


--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html

[Index of Archives]     [Linux Media]     [Linux Input]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]     [Old Linux USB Devel Archive]

  Powered by Linux