Re: [PATCH v2 0/2] ARM: shmobile: r8a7791: add for USB-DMAC

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hello Shimoda-san,

(Dropping the DT maintainers from CC and adding Linus Walleij, Kishon Vijay 
Abraham and Felipe Balbi)

On Tuesday 07 April 2015 16:53:49 Yoshihiro Shimoda wrote:
> This patch set is based on renesas.git / renesas-devel-20150406-v4.0-rc6
> tag. (commit id = 8acf8f0880b6a142e6291b9a7d81f2f38c9425ac)
> 
> This patch set is related to the usb-dmac driver and renesas_usbhs driver.
> And these drivers have been merged in each subsystem:
> 
> [ slave-dma repository ]
> https://git.kernel.org/cgit/linux/kernel/git/vkoul/slave-dma.git/commit/?h=f
> or-linus&id§267831565030ab94dab76eb1afe5d4b63a1009
> https://git.kernel.org/cgit/linux/kernel/git/vkoul/slave-dma.git/commit/?h> for-linus&id\f1c8ff32fa29e425b4938934c21afdb81104431
> 
> [ usb repository ]
> https://git.kernel.org/cgit/linux/kernel/git/balbi/usb.git/commit/?h=testing
> /next&idz96b78464bd8ba72c1c3095c543c1402db59e35
> https://git.kernel.org/cgit/linux/kernel/git/balbi/usb.git/commit/?h=testin
> g/next&id›53d9af7aac09cf249d72bfbf15f08e47c4f7fe
> https://git.kernel.org/cgit/linux/kernel/git/balbi/usb.git/commit/?h=testin
> g/next&id«330cf3888d8e0779fa05a243d53ba9f53a7ba9
> 
> Changes from v1:
>  - Rebase the latest renesas-devel tag.
> 
> Yoshihiro Shimoda (2):
>   ARM: shmobile: r8a7791: add USB-DMAC device nodes
>   ARM: shmobile: r8a7791: Enable DMA for HSUSB

I've successfully tested USB-DMAC integration (congratulations for the good 
work !), but ran into several issues that I wanted to discuss with you.

Both issues are I believe related to the fact that the HSUSB and EHCI/OHCI 
controllers share the same PHY and the same pins.

When both drivers are loaded, the following messages are printed to the kernel 
log.

[    8.917418] sh-pfc e6060000.pfc: pin GP_7_23 already requested by 
ee090000.pci; cannot claim for e6590000.usb
[    8.927594] sh-pfc e6060000.pfc: pin-247 (e6590000.usb) status -22
[    8.933913] sh-pfc e6060000.pfc: could not request pin 247 (GP_7_23) from 
group usb0  on device sh-pfc
[    8.943990] renesas_usbhs e6590000.usb: Error applying setting, reverse 
things back

This is caused by the pci0 and hsusb DT nodes referencing the same default pin 
configuration node. There should be no issue in practice as the pin 
configuration is already applied through the other device, but I'd still like 
to find a fix to avoid the error message.

The other issue is that the renesas_hsusb and ehci drivers compete to control 
the same PHY. The phy-rcar-gen2 driver creates two Linux PHYs for each 
physical PHY (called channel in the driver) to ensure that each driver can get 
its own PHY instance. Arbitration is then handled in the PHY .init() handler 
which returns -EBUSY if another driver already controls the channel. The error 
value is propagated up to usbhsc_power_ctrl() where it's then ignored. This 
doesn't look like a good way to handled the shared PHY, but I'm not familiar 
enough with the PHY subsystem to know how to fix it.

>  arch/arm/boot/dts/r8a7791.dtsi | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)

-- 
Regards,

Laurent Pinchart