Re: [PATCH 1/2] usb: dwc2: Option to disable dma descriptor mode

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

 



On Tue, May 06, 2014 at 06:21:02PM +0000, Paul Zimmerman wrote:
> > From: dinguyen@xxxxxxxxxx [mailto:dinguyen@xxxxxxxxxx]
> > Sent: Monday, May 05, 2014 3:23 PM
> > 
> > Even though the IP supports Descriptor DMA mode, it does not support SPLIT
> > transactions in this mode. Since the driver can get the Descriptor DMA mode
> > support from hardware, the driver in its currently form cannot fully support
> > LS/FS devices connected to a HS Hub when Descriptor DMA mode is enabled in the
> > driver. Thus, we give the option to disable Descriptor DMA from device tree.
> 
> Hi Dinh,
> 
> Instead of this patch, how about if we make the driver default to buffer
> DMA mode instead, and if anyone wants to use descriptor DMA mode, they
> can add a DT property for that? I don't think anyone will want that,
> since as you say it doesn't fully support LS/FS devices in that mode.
> 
> The driver originally worked like that. I guess the default got changed by
> one of Matthijs' patches, and I didn't notice it.

if this is the case, I guess you could call it a regression - well, it
_did_ break LS/FS use cases - and still merge it during the -rc cycle.

cheers

-- 
balbi

Attachment: signature.asc
Description: Digital signature


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

  Powered by Linux