RE: [PATCH] usb: renesas_usbhs: Revise the binding document about the dma-names

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Hi Mark,

> 
> On Wed, Apr 08, 2015 at 11:42:24AM +0100, Yoshihiro Shimoda wrote:
> > Since the DT should describe the hardware (not the driver limitation),
> > This patch revises the binding document about the dma-names to change
> > simple numbering as "ch%d" instead of "tx<n>" and "rx<n>".
> 
> The naming given in this patch looks more sensible to me.

Thank you for your comment!

> > Also this patch fixes the actual code of renesas_usbhs driver to handle
> > the new dma-names.
> >
> > Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
> > ---
> >  This patch is based on Felipe's usb.bit / testing/next branch.
> >  (commit id = bbc78c07a51f6fd29c227b1220a9016e585358ba)
> 
> I take it the existing driver and binding haven't hit mainline, and
> therefore there are no users yet?

That's correct. At the moment, nobody uses the dma-names in the node of
renesas_usbhs yet.

Best regards,
Yoshihiro Shimoda

> Mark.
> 
> >
> >  Geert is pointed out about this issue:
> >  https://www.mail-archive.com/devicetree@xxxxxxxxxxxxxxx/msg68401.html
> >
> >  .../devicetree/bindings/usb/renesas_usbhs.txt      |  6 ++----
> >  drivers/usb/renesas_usbhs/fifo.c                   | 24 ++++++++++++++--------
> >  2 files changed, 17 insertions(+), 13 deletions(-)
> >
> > diff --git a/Documentation/devicetree/bindings/usb/renesas_usbhs.txt
> b/Documentation/devicetree/bindings/usb/renesas_usbhs.txt
> > index dc2a18f..ddbe304 100644
> > --- a/Documentation/devicetree/bindings/usb/renesas_usbhs.txt
> > +++ b/Documentation/devicetree/bindings/usb/renesas_usbhs.txt
> > @@ -15,10 +15,8 @@ Optional properties:
> >    - phys: phandle + phy specifier pair
> >    - phy-names: must be "usb"
> >    - dmas: Must contain a list of references to DMA specifiers.
> > -  - dma-names : Must contain a list of DMA names:
> > -   - tx0 ... tx<n>
> > -   - rx0 ... rx<n>
> > -    - This <n> means DnFIFO in USBHS module.
> > +  - dma-names : named "ch%d", where %d is the channel number ranging from zero
> > +                to the number of channels (DnFIFOs) minus one.
> >
> >  Example:
> >  	usbhs: usb@e6590000 {
> > diff --git a/drivers/usb/renesas_usbhs/fifo.c b/drivers/usb/renesas_usbhs/fifo.c
> > index 8597cf9..bc23b4a 100644
> > --- a/drivers/usb/renesas_usbhs/fifo.c
> > +++ b/drivers/usb/renesas_usbhs/fifo.c
> > @@ -1227,15 +1227,21 @@ static void usbhsf_dma_init_dt(struct device *dev, struct usbhs_fifo *fifo,
> >  {
> >  	char name[16];
> >
> > -	snprintf(name, sizeof(name), "tx%d", channel);
> > -	fifo->tx_chan = dma_request_slave_channel_reason(dev, name);
> > -	if (IS_ERR(fifo->tx_chan))
> > -		fifo->tx_chan = NULL;
> > -
> > -	snprintf(name, sizeof(name), "rx%d", channel);
> > -	fifo->rx_chan = dma_request_slave_channel_reason(dev, name);
> > -	if (IS_ERR(fifo->rx_chan))
> > -		fifo->rx_chan = NULL;
> > +	/*
> > +	 * To avoid complex handing for DnFIFOs, the driver uses each
> > +	 * DnFIFO as TX or RX direction (not bi-direction).
> > +	 * So, the driver uses odd channels for TX, even channels for RX.
> > +	 */
> > +	snprintf(name, sizeof(name), "ch%d", channel);
> > +	if (channel & 1) {
> > +		fifo->tx_chan = dma_request_slave_channel_reason(dev, name);
> > +		if (IS_ERR(fifo->tx_chan))
> > +			fifo->tx_chan = NULL;
> > +	} else {
> > +		fifo->rx_chan = dma_request_slave_channel_reason(dev, name);
> > +		if (IS_ERR(fifo->rx_chan))
> > +			fifo->rx_chan = NULL;
> > +	}
> >  }
> >
> >  static void usbhsf_dma_init(struct usbhs_priv *priv, struct usbhs_fifo *fifo,
> > --
> > 1.9.1
> >
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