From mboxrd@z Thu Jan 1 00:00:00 1970 From: khilman@baylibre.com (Kevin Hilman) Date: Fri, 09 Sep 2016 10:04:19 -0700 Subject: [PATCH 4/7] phy: meson: add USB2 PHY support for Meson8b and GXBB In-Reply-To: (Martin Blumenstingl's message of "Fri, 9 Sep 2016 18:14:03 +0200") References: <20160904213152.25837-1-martin.blumenstingl@googlemail.com> <20160904213152.25837-5-martin.blumenstingl@googlemail.com> Message-ID: To: linus-amlogic@lists.infradead.org List-Id: linus-amlogic.lists.infradead.org Martin Blumenstingl writes: > On Fri, Sep 9, 2016 at 5:33 PM, Kevin Hilman wrote: >> However, the problem with all of the solutions proposed (runtime PM ones >> included) is that we're forcing a board-specific design issue (2 devices >> sharing a reset line) into a driver that should not have any >> board-specific assumptions in it. >> >> For example, if this driver is used on another platform where different >> PHYs have different reset lines, then one of them (the unlucky one who >> is not probed first) will never get reset. So any form of per-device >> ref-counting is not a portable solution. > > maybe we should also consider Ben's solution: he played with the USB > PHY on his Meson8b board. His approach was to have only one USB PHY > driver instance which exposes two PHYs. > The downside of this: the driver would have to know the offset of the > PHYs (0x0 for the first PHY, 0x20 for the second), but we could handle > the reset using runtime PM without any hacks. > I checked the USB PHY reference driver: it seems that there will be a > new USB PHY with the GXL/GXM SoCs. > So maybe we could live with the assumption that the PHYs are at > consecutive addresses. But isn't that also forcing us to make board-specific assumptions inside the driver. Kevin From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Return-Path: From: Kevin Hilman To: Martin Blumenstingl Cc: Ben Dooks , mark.rutland@arm.com, devicetree@vger.kernel.org, gregkh@linuxfoundation.org, johnyoun@synopsys.com, will.deacon@arm.com, mturquette@baylibre.com, linux-usb@vger.kernel.org, sboyd@codeaurora.org, kishon@ti.com, robh+dt@kernel.org, catalin.marinas@arm.com, carlo@caione.org, linux-amlogic@lists.infradead.org, linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org, jbrunet@baylibre.com Subject: Re: [PATCH 4/7] phy: meson: add USB2 PHY support for Meson8b and GXBB References: <20160904213152.25837-1-martin.blumenstingl@googlemail.com> <20160904213152.25837-5-martin.blumenstingl@googlemail.com> Date: Fri, 09 Sep 2016 10:04:19 -0700 In-Reply-To: (Martin Blumenstingl's message of "Fri, 9 Sep 2016 18:14:03 +0200") Message-ID: MIME-Version: 1.0 Content-Type: text/plain List-ID: Martin Blumenstingl writes: > On Fri, Sep 9, 2016 at 5:33 PM, Kevin Hilman wrote: >> However, the problem with all of the solutions proposed (runtime PM ones >> included) is that we're forcing a board-specific design issue (2 devices >> sharing a reset line) into a driver that should not have any >> board-specific assumptions in it. >> >> For example, if this driver is used on another platform where different >> PHYs have different reset lines, then one of them (the unlucky one who >> is not probed first) will never get reset. So any form of per-device >> ref-counting is not a portable solution. > > maybe we should also consider Ben's solution: he played with the USB > PHY on his Meson8b board. His approach was to have only one USB PHY > driver instance which exposes two PHYs. > The downside of this: the driver would have to know the offset of the > PHYs (0x0 for the first PHY, 0x20 for the second), but we could handle > the reset using runtime PM without any hacks. > I checked the USB PHY reference driver: it seems that there will be a > new USB PHY with the GXL/GXM SoCs. > So maybe we could live with the assumption that the PHYs are at > consecutive addresses. But isn't that also forcing us to make board-specific assumptions inside the driver. Kevin From mboxrd@z Thu Jan 1 00:00:00 1970 From: khilman@baylibre.com (Kevin Hilman) Date: Fri, 09 Sep 2016 10:04:19 -0700 Subject: [PATCH 4/7] phy: meson: add USB2 PHY support for Meson8b and GXBB In-Reply-To: (Martin Blumenstingl's message of "Fri, 9 Sep 2016 18:14:03 +0200") References: <20160904213152.25837-1-martin.blumenstingl@googlemail.com> <20160904213152.25837-5-martin.blumenstingl@googlemail.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Martin Blumenstingl writes: > On Fri, Sep 9, 2016 at 5:33 PM, Kevin Hilman wrote: >> However, the problem with all of the solutions proposed (runtime PM ones >> included) is that we're forcing a board-specific design issue (2 devices >> sharing a reset line) into a driver that should not have any >> board-specific assumptions in it. >> >> For example, if this driver is used on another platform where different >> PHYs have different reset lines, then one of them (the unlucky one who >> is not probed first) will never get reset. So any form of per-device >> ref-counting is not a portable solution. > > maybe we should also consider Ben's solution: he played with the USB > PHY on his Meson8b board. His approach was to have only one USB PHY > driver instance which exposes two PHYs. > The downside of this: the driver would have to know the offset of the > PHYs (0x0 for the first PHY, 0x20 for the second), but we could handle > the reset using runtime PM without any hacks. > I checked the USB PHY reference driver: it seems that there will be a > new USB PHY with the GXL/GXM SoCs. > So maybe we could live with the assumption that the PHYs are at > consecutive addresses. But isn't that also forcing us to make board-specific assumptions inside the driver. Kevin From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kevin Hilman Subject: Re: [PATCH 4/7] phy: meson: add USB2 PHY support for Meson8b and GXBB Date: Fri, 09 Sep 2016 10:04:19 -0700 Message-ID: References: <20160904213152.25837-1-martin.blumenstingl@googlemail.com> <20160904213152.25837-5-martin.blumenstingl@googlemail.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: In-Reply-To: (Martin Blumenstingl's message of "Fri, 9 Sep 2016 18:14:03 +0200") Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Martin Blumenstingl Cc: Ben Dooks , mark.rutland-5wv7dgnIgG8@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org, johnyoun-HKixBCOQz3hWk0Htik3J/w@public.gmane.org, will.deacon-5wv7dgnIgG8@public.gmane.org, mturquette-rdvid1DuHRBWk0Htik3J/w@public.gmane.org, linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, sboyd-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org, kishon-l0cyMroinI0@public.gmane.org, robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, catalin.marinas-5wv7dgnIgG8@public.gmane.org, carlo-KA+7E9HrN00dnm+yROfE0A@public.gmane.org, linux-amlogic-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-clk-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, jbrunet-rdvid1DuHRBWk0Htik3J/w@public.gmane.org List-Id: devicetree@vger.kernel.org Martin Blumenstingl writes: > On Fri, Sep 9, 2016 at 5:33 PM, Kevin Hilman wrote: >> However, the problem with all of the solutions proposed (runtime PM ones >> included) is that we're forcing a board-specific design issue (2 devices >> sharing a reset line) into a driver that should not have any >> board-specific assumptions in it. >> >> For example, if this driver is used on another platform where different >> PHYs have different reset lines, then one of them (the unlucky one who >> is not probed first) will never get reset. So any form of per-device >> ref-counting is not a portable solution. > > maybe we should also consider Ben's solution: he played with the USB > PHY on his Meson8b board. His approach was to have only one USB PHY > driver instance which exposes two PHYs. > The downside of this: the driver would have to know the offset of the > PHYs (0x0 for the first PHY, 0x20 for the second), but we could handle > the reset using runtime PM without any hacks. > I checked the USB PHY reference driver: it seems that there will be a > new USB PHY with the GXL/GXM SoCs. > So maybe we could live with the assumption that the PHYs are at > consecutive addresses. But isn't that also forcing us to make board-specific assumptions inside the driver. Kevin -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html