[U-Boot] [PATCH 2/6] usb:udc:samsung: Remove redundant cache operation from Samsung UDC driver

Lukasz Majewski
2014-02-04T06:23:38Z

Hi Marek,

> On Monday, February 03, 2014 at 09:05:06 AM, Lukasz Majewski wrote:
>
> [...]
>
> > > > To sum up:
> > > >
> > > > 1. s3c_udc_ep0_zlp - EP0 ZLP packets don't need to invalidate
> > > > the cache (since it is zero length transmission)
> > > >
> > > > 2. s3c_udc_pre_setup - cache invalidation is not needed when I
> > > > setup buffer for OUT EP0 transmission.
> > > >
> > > > The above two invalidation calls had been added by me, and are
> > > > mine mistakes. Those don't contribute to transmission speed up
> > > > (and shall be regarded as a cosmetic changes)
> > > >
> > > > 3. setdma_rx - here I invalidate parts of the s3c UDC driver's
> > > > internal buffer. This call is not needed anymore since we reuse
> > > > the buffers passed from gadgets.
> > >
> > > And you do correct cache management on those in the UDC driver or
> > > in the gadget driver ?
> >
> > For download, buffers are allocated in gadgets. Then buffer is
> > passed to the UDC driver in a USB request.
> > After receiving data via USB the UDC driver takes care to invalidate
> > cache, hence the gadget can work on the data.
> >
> > Cache management is performed in the UDC driver.
>
> OK, this is the correct place. I just wanted to make sure about this.
> Thanks :)

No problem :-)

>
> > > > This is the key speed improvement here.
> > >
> > > This should be in the commit message really ;-)
> >
> > I wrongly assumed, that code explains what was the rationale :-).
> > I'm going to prepare more verbose commit message for v2.
>
> Please do, thanks!
>
> Best regards,
> Marek Vasut

--
Best regards,

Lukasz Majewski

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