Hi Geert-san,
> Hi Shimoda-san,
>
> On Tue, Apr 7, 2015 at 9:53 AM, Yoshihiro Shimoda
> <yoshihiro.shimoda...@renesas.com> wrote:
> > This patch adds DMA properties to the HSUSB node.
>
> Thank you for your patch!
Thank you for your review!
> > Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda...@renesas.com>
> > ---
> > arch/arm/boot/dts/r8a7791.dtsi | 3 +++
> > 1 file changed, 3 insertions(+)
> >
> > diff --git a/arch/arm/boot/dts/r8a7791.dtsi b/arch/arm/boot/dts/r8a7791.dtsi
> > index db3772e..5f20ad4 100644
> > --- a/arch/arm/boot/dts/r8a7791.dtsi
> > +++ b/arch/arm/boot/dts/r8a7791.dtsi
> > @@ -722,6 +722,9 @@
> > renesas,buswait = <4>;
> > phys = <&usb0 1>;
> > phy-names = "usb";
> > + dmas = <&usb_dmac0 0>, <&usb_dmac0 1>,
> > + <&usb_dmac1 0>, <&usb_dmac1 1>;
> > + dma-names = "rx0", "tx1", "rx2", "tx3";
>
> The numbering looks a bit strange, given the code looks up both tx and rx
> DMA channels for each channel index. Is it correct?
>
> The binding documentation (which lacks on example) states:
>
> - dma-names : Must contain a list of DMA names:
> - tx0 ... tx<n>
> - rx0 ... rx<n>
> - This <n> means DnFIFO in USBHS module.
>
> As there are 4 DnFIFOs, I'd expect tx0..tx3 and rx0..rx3.
>
> Can you please clarify?
I wrote some information below.
But, since it is complex hardware, I don't know I can explain this as well...
At first, R-Car Gen2 has 2 USB-DMACs and 4 channels:
USB-DMAC 0: ch0
USB-DMAC 0: ch1
USB-DMAC 1: ch0
USB-DMAC 1: ch1
Remarks: I don't know why but performance of USB-DMAC 0 is good than USB-DMAC 1.
(Please refer to the Table 64.1 of the datasheet.)
So, I wrote dmas parameter in hsusb as the following:
> > + dmas = <&usb_dmac0 0>, <&usb_dmac0 1>,
> > + <&usb_dmac1 0>, <&usb_dmac1 1>;
And, R-Car Gen2 has 4 DnFIFOs in HSUSB. to avoid complex handling for DnFIFOs,
the renesas_usbhs driver uses each DnFIFO as TX or RX direction (not
bi-direction).
So, I wrote dma-names parameter as the following:
> > + dma-names = "rx0", "tx1", "rx2", "tx3";
- D0FIFO as RX (Also it is connected to USB-DMAC 0: ch0)
- D1FIFO as TX (Also it is connected to USB-DMAC 0: ch1)
- D2FIFO as RX (Also it is connected to USB-DMAC 1: ch0)
- D3FIFO as TX (Also it is connected to USB-DMAC 1: ch1)
Best regards,
Yoshihiro Shimoda
> Thanks!
>
> Gr{oetje,eeting}s,
>
> Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 --
> ge...@linux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like
> that.
> -- Linus Torvalds
