Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759277Ab3JONuA (ORCPT ); Tue, 15 Oct 2013 09:50:00 -0400 Received: from bear.ext.ti.com ([192.94.94.41]:53402 "EHLO bear.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758955Ab3JONt6 (ORCPT ); Tue, 15 Oct 2013 09:49:58 -0400 Message-ID: <525D47C3.207@ti.com> Date: Tue, 15 Oct 2013 16:48:51 +0300 From: Roger Quadros User-Agent: Mozilla/5.0 (X11; Linux i686; rv:16.0) Gecko/20121011 Thunderbird/16.0.1 MIME-Version: 1.0 To: , Vivek Gautam CC: Kishon Vijay Abraham I , , , , , , , , , , , , , , , , , , , , Subject: Re: [PATCH 2/7] usb: dwc3: adapt dwc3 core to use Generic PHY Framework References: <1378136591-7463-1-git-send-email-kishon@ti.com> <1378136591-7463-3-git-send-email-kishon@ti.com> <525814A9.7060106@ti.com> <525BB8C0.1070802@ti.com> <525BC5A9.3060904@ti.com> <20131015115741.GD11380@radagast> <525D30C2.8060208@ti.com> <20131015131934.GG11380@radagast> In-Reply-To: <20131015131934.GG11380@radagast> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6948 Lines: 188 On 10/15/2013 04:19 PM, Felipe Balbi wrote: > Hi, > > On Tue, Oct 15, 2013 at 03:10:42PM +0300, Roger Quadros wrote: >>>>>>> @@ -665,6 +669,9 @@ struct dwc3 { >>>>>>> struct usb_phy *usb2_phy; >>>>>>> struct usb_phy *usb3_phy; >>>>>>> >>>>>>> + struct phy *usb2_generic_phy; >>>>>>> + struct phy *usb3_generic_phy; >>>>>>> + >>>>>>> void __iomem *regs; >>>>>>> size_t regs_size; >>>>>>> >>>>>>> >>>>> >>>>> Do you have any suggestions on how to get only individual PHYs? like only >>>>> usb2phy or usb3phy? >>>> >>>> My earlier understanding was that both PHYs are needed only if .speed is "super-speed" >>>> and only usb2phy is needed for "high-speed". But as per Vivek's email it seems >>>> Samsung's exynos5 SoC doesn't need usb2phy for "super-speed". >>>> >>>> So to keeps things flexible, I can propose the following approach >>>> - if speed == 'high-speed' usb2phy must be present. usb3phy will be ignored if supplied. >>>> - if speed == 'super-speed' usb3phy must be present and usb2phy is optional but must be >>>> initialized if supplied. >>>> - if speed is not specified, we default to 'super-speed'. >>>> >>>> Felipe, does this address the issue you were facing with OMAP5? >>> >>> on OMAP5 we cannot skip USB3 PHY initialization. But then it becomes a >>> question of supporting a test feature (in OMAP5 case it would be cool to >>> force controller to lower speeds for testing) or coping with a broken >>> DTS. >>> >> >> I don't think we can protect ourselves from all possible broken >> configurations of DTS. >> I would vote for simplicity and maximum flexibility. >> >> So IMO we should just depend on DTS to provide the phys that are >> needed by the platform. >> In the driver we initialize whatever PHY is provided and don't >> complain if any or even all PHYs are missing. > > considering that DTS is an ABI, I really think eventually we *will* have > broken DTBs burned into ROM and we will have to find ways to work with > those too. Same thing already happens today with ACPI tables. > >> If this is not good enough then could you please suggest an >> alternative? Thanks. > > The alternative would be to mandate nop xceiv for the "missing" PHY, but > that doesn't solve anything, really, as DTS authors might still forget > about the NOP xceiv and you can argue that forcing NOP xceiv would be a > SW configuration. > > So, perhaps we go with the approach that all PHYs are optional, and > here's my original patch which makes USB3 PHY optional: > > commit 979b84f96e4b7559b596b2933ae198aba267f260 > Author: Felipe Balbi > Date: Sun Jun 30 18:39:23 2013 +0300 > > usb: dwc3: core: make USB3 PHY optional > > If we want a port to work at any speed lower > than Superspeed, it makes no sense to even > initialize/power up the USB3 transceiver, > provided it won't be used. > > We can use the oportunity to save some power > and leave the superspeed transceiver powered > off. > > There is at least one such case which is > Texas Instruments' AM437x which has one > of its USB3 ports without a matching USB3 > PHY (that port is hardwired to work on USB2 > only). > > Signed-off-by: Felipe Balbi > > diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c > index 74f9cf0..7a5ab93 100644 > --- a/drivers/usb/dwc3/core.c > +++ b/drivers/usb/dwc3/core.c > @@ -387,16 +387,34 @@ static int dwc3_probe(struct platform_device *pdev) > if (node) { > dwc->maximum_speed = of_usb_get_maximum_speed(node); > > - dwc->usb2_phy = devm_usb_get_phy_by_phandle(dev, "usb-phy", 0); > - dwc->usb3_phy = devm_usb_get_phy_by_phandle(dev, "usb-phy", 1); > + switch (dwc->maximum_speed) { > + case USB_SPEED_SUPER: > + dwc->usb2_phy = devm_usb_get_phy_by_phandle(dev, "usb-phy", 0); > + dwc->usb3_phy = devm_usb_get_phy_by_phandle(dev, "usb-phy", 1); > + break; > + case USB_SPEED_HIGH: > + case USB_SPEED_FULL: > + case USB_SPEED_LOW: > + dwc->usb2_phy = devm_usb_get_phy_by_phandle(dev, "usb-phy", 0); > + break; > + } > > dwc->needs_fifo_resize = of_property_read_bool(node, "tx-fifo-resize"); > dwc->dr_mode = of_usb_get_dr_mode(node); > } else if (pdata) { > dwc->maximum_speed = pdata->maximum_speed; > > - dwc->usb2_phy = devm_usb_get_phy(dev, USB_PHY_TYPE_USB2); > - dwc->usb3_phy = devm_usb_get_phy(dev, USB_PHY_TYPE_USB3); > + switch (dwc->maximum_speed) { > + case USB_SPEED_SUPER: > + dwc->usb2_phy = devm_usb_get_phy(dev, USB_PHY_TYPE_USB2); > + dwc->usb3_phy = devm_usb_get_phy(dev, USB_PHY_TYPE_USB3); > + break; > + case USB_SPEED_HIGH: > + case USB_SPEED_FULL: > + case USB_SPEED_LOW: > + dwc->usb2_phy = devm_usb_get_phy(dev, USB_PHY_TYPE_USB2); > + break; > + } What if we try to get both PHYs irrespective of 'maximum_speed' but based on presence of phandle/pdata. That way there is some control in the adaptation code (dts/pdata) as to which PHYs needs to be initialized for that particular instance. This is because there doesn't seem to be a consensus between different designs. e.g. omap5 needs both phys for 'high-speed' whereas exynos5250 needs just the usb3 phy for 'super-speed' > > dwc->needs_fifo_resize = pdata->tx_fifo_resize; > dwc->dr_mode = pdata->dr_mode; > @@ -424,19 +442,21 @@ static int dwc3_probe(struct platform_device *pdev) > return -EPROBE_DEFER; > } > > - if (IS_ERR(dwc->usb3_phy)) { > - ret = PTR_ERR(dwc->usb3_phy); > + if (dwc->maximum_speed == USB_SPEED_SUPER) { > + if (IS_ERR(dwc->usb3_phy)) { > + ret = PTR_ERR(dwc->usb3_phy); > > - /* > - * if -ENXIO is returned, it means PHY layer wasn't > - * enabled, so it makes no sense to return -EPROBE_DEFER > - * in that case, since no PHY driver will ever probe. > - */ > - if (ret == -ENXIO) > - return ret; > + /* > + * if -ENXIO is returned, it means PHY layer wasn't > + * enabled, so it makes no sense to return -EPROBE_DEFER > + * in that case, since no PHY driver will ever probe. > + */ > + if (ret == -ENXIO) > + return ret; > > - dev_err(dev, "no usb3 phy configured\n"); > - return -EPROBE_DEFER; > + dev_err(dev, "no usb3 phy configured\n"); > + return -EPROBE_DEFER; > + } > } > > dwc->xhci_resources[0].start = res->start; > > > what you guys are saying though, is that every PHY should be optional. > > Do we have any device which doesn't provide USB2 PHY, only USB3 ? Dude, > that's so non-standard! USB *must* be backwards compatible so I'd expect > USB2 PHY to always be available. > Maybe the USB2 PHY hardware is there on the Exynos5250 but it just doesn't have discrete power control. Vivek? cheers, -roger -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/