From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sergei Shtylyov Subject: Re: [PATCH v3] phy: Renesas R-Car Gen2 PHY driver Date: Thu, 22 May 2014 02:23:44 +0400 Message-ID: <537D2770.2040605@cogentembedded.com> References: <201404120415.43761.sergei.shtylyov@cogentembedded.com> <534B77E2.8060901@ti.com> <53557BFE.5020908@cogentembedded.com> <53578FA8.6040607@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <53578FA8.6040607@ti.com> Sender: linux-doc-owner@vger.kernel.org To: Kishon Vijay Abraham I , devicetree@vger.kernel.org, robh+dt@kernel.org, pawel.moll@arm.com, mark.rutland@arm.com, ijc+devicetree@hellion.org.uk, galak@codeaurora.org, grant.likely@linaro.org Cc: linux-sh@vger.kernel.org, magnus.damm@gmail.com, linux-doc@vger.kernel.org, rdunlap@infradead.org List-Id: devicetree@vger.kernel.org Hello. On 04/23/2014 02:02 PM, Kishon Vijay Abraham I wrote: >>>> This PHY, though formally being a part of Renesas USBHS controller, contains >>>> the >>>> UGCTRL2 register that controls multiplexing of the USB ports (Renesas calls >>>> them >>>> channels) to the different USB controllers: channel 0 can be connected to >>>> either >>>> PCI EHCI/OHCI or USBHS controllers, channel 2 can be connected to PCI EHCI/OHCI >>>> or xHCI controllers. >>>> This is a new driver for this USB PHY currently already supported under >>>> drivers/ >>>> usb/phy/. The reason for writing the new driver was the requirement that the >>>> multiplexing of USB channels to the controller be dynamic, depending on what >>>> USB drivers are loaded, rather than static as provided by the old driver. >>>> The infrastructure provided by drivers/phy/phy-core.c seems to fit that purpose >>>> ideally. The new driver only supports device tree probing for now. >>>> Signed-off-by: Sergei Shtylyov >> [...] >>>> Index: linux-phy/drivers/phy/phy-rcar-gen2.c >>>> =================================================================== >>>> --- /dev/null >>>> +++ linux-phy/drivers/phy/phy-rcar-gen2.c >>>> @@ -0,0 +1,283 @@ >> [...] >>>> +static int rcar_gen2_phy_probe(struct platform_device *pdev) >>>> +{ >> [...] >>>> + drv->phys[0][0].select_mask = USBHS_UGCTRL2_USB0SEL; >>>> + drv->phys[0][0].select_value = USBHS_UGCTRL2_USB0SEL_PCI; >>>> + drv->phys[0][1].select_mask = USBHS_UGCTRL2_USB0SEL; >>>> + drv->phys[0][1].select_value = USBHS_UGCTRL2_USB0SEL_HS_USB; >>>> + drv->phys[2][0].select_mask = USBHS_UGCTRL2_USB2SEL; >>>> + drv->phys[2][0].select_value = USBHS_UGCTRL2_USB2SEL_PCI; >>>> + drv->phys[2][1].select_mask = USBHS_UGCTRL2_USB2SEL; >>>> + drv->phys[2][1].select_value = USBHS_UGCTRL2_USB2SEL_USB30; >>>> + >>>> + for (i = 0; i < NUM_USB_CHANNELS; i++) { >>> Instead of hard coding the number of channels, >> It's hard coded in the hardware. We can even decrease that number to 2 as > right, that's why thought dt should have that information. So you want a dedicated property for that or you meant something else? >> for the channel #1 we have nothing to do, regardless of whether it's present or >> not... >>> we can model the channels (PHYs) as sub-nodes of the main PHY >> Hm, I don't think such representation would be adequate: the channels >> themselves do not usually correspond to any particular PHY, that's why I used >> #phy-cells = <2>. >>> in dt and use it to create individual PHYs. >> Well, we probably can... however, I fail to see any immediate gain from >> it here... >> I have to ask why you've selected this particular driver for such DT >> representation experiments, despite it not being the first one supporting >> multiple PHYs? > just that it didn't strike before.. but I think all multiple PHYs should be > modelled this way. I've basically reimplemented the driver to parse the info from the subnodes and it's now became larger in size, not smaller. :-/ Overall, I'm not content with the changes, nor do I think such a change in the DT representation was a great idea... > Thanks > Kishon WBR, Sergei