From: Alan Stern <stern@rowland.harvard.edu> To: Alexander Dahl <ada@thorsis.com> Cc: linux-usb@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, rca@thorsis.com Subject: Re: Enable HSIC Host Port on Atmel/Microchip SAMA5D2 Date: Mon, 23 Aug 2021 10:00:52 -0400 [thread overview] Message-ID: <20210823140052.GA120849@rowland.harvard.edu> (raw) In-Reply-To: <2869763.XZdSvA6Ref@ada> On Mon, Aug 23, 2021 at 11:24:35AM +0200, Alexander Dahl wrote: > Hello, > > for a new embedded board featuring a Microchip SAMA5D2 SoC (64 MiB SiP variant > SAMA5D27C-D5M) we connected the third USB host port (HSIC only) with an > USB3503 hub chip. This doesn't work out of the box with the Linux kernel > currently, because neither the SoC nor the kernel does enable the HSIC > interface by default. > > That SoC has three USB host ports, from the SAMA5D2 Series Datasheet [1] I > learned there's a flag in an EHCI register, which has to be set to enable the > HSIC interface on port C, the third port. (Section "41.7.14 EHCI: REG08 - HSIC > Enable/Disable" of the datasheet.) I suppose that register is vendor specific. > The register definitions in '/include/linux/usb/ehci_def.h' do not contain > that register. > > Where would I add that register definition and set that flag in the kernel > then? I suppose in the vendor specific ehci driver? > That would be 'drivers/usb/host/ehci-atmel.c' right? That is where you would set the flag. You might want to put the register definition in ehci_def.h, with the other definitions. > Since that feature is optional (other boards don't need to turn on hsic on > that port), some driver specific new device tree binding would be necessary, > right? I suppose that would have to be documented in 'Documentation/ > devicetree/bindings/usb/atmel-usb.txt' right? (Or that would have to be > converted to yaml first?) Yes, it would have to go into the device tree data somehow. I don't know the best way to do this; people who know more about DT may be able to tell you. > Is this the right track? If yes, I'm going to develop patches for this. > Otherwise any hint into the right direction are highly appreciated. Yes, this is the right approach. Alan Stern > FWIW, I'm not the first one struggling [2] with this problem. ;-) > > Greets > Alex > > [1] https://www.microchip.com/en-us/product/ATSAMA5D27C-D5M#document-table > [2] https://community.atmel.com/forum/sama5d2-using-hsic-under-linux
WARNING: multiple messages have this Message-ID (diff)
From: Alan Stern <stern@rowland.harvard.edu> To: Alexander Dahl <ada@thorsis.com> Cc: linux-usb@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, rca@thorsis.com Subject: Re: Enable HSIC Host Port on Atmel/Microchip SAMA5D2 Date: Mon, 23 Aug 2021 10:00:52 -0400 [thread overview] Message-ID: <20210823140052.GA120849@rowland.harvard.edu> (raw) In-Reply-To: <2869763.XZdSvA6Ref@ada> On Mon, Aug 23, 2021 at 11:24:35AM +0200, Alexander Dahl wrote: > Hello, > > for a new embedded board featuring a Microchip SAMA5D2 SoC (64 MiB SiP variant > SAMA5D27C-D5M) we connected the third USB host port (HSIC only) with an > USB3503 hub chip. This doesn't work out of the box with the Linux kernel > currently, because neither the SoC nor the kernel does enable the HSIC > interface by default. > > That SoC has three USB host ports, from the SAMA5D2 Series Datasheet [1] I > learned there's a flag in an EHCI register, which has to be set to enable the > HSIC interface on port C, the third port. (Section "41.7.14 EHCI: REG08 - HSIC > Enable/Disable" of the datasheet.) I suppose that register is vendor specific. > The register definitions in '/include/linux/usb/ehci_def.h' do not contain > that register. > > Where would I add that register definition and set that flag in the kernel > then? I suppose in the vendor specific ehci driver? > That would be 'drivers/usb/host/ehci-atmel.c' right? That is where you would set the flag. You might want to put the register definition in ehci_def.h, with the other definitions. > Since that feature is optional (other boards don't need to turn on hsic on > that port), some driver specific new device tree binding would be necessary, > right? I suppose that would have to be documented in 'Documentation/ > devicetree/bindings/usb/atmel-usb.txt' right? (Or that would have to be > converted to yaml first?) Yes, it would have to go into the device tree data somehow. I don't know the best way to do this; people who know more about DT may be able to tell you. > Is this the right track? If yes, I'm going to develop patches for this. > Otherwise any hint into the right direction are highly appreciated. Yes, this is the right approach. Alan Stern > FWIW, I'm not the first one struggling [2] with this problem. ;-) > > Greets > Alex > > [1] https://www.microchip.com/en-us/product/ATSAMA5D27C-D5M#document-table > [2] https://community.atmel.com/forum/sama5d2-using-hsic-under-linux _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-08-23 14:00 UTC|newest] Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-08-23 9:24 Enable HSIC Host Port on Atmel/Microchip SAMA5D2 Alexander Dahl 2021-08-23 9:24 ` Alexander Dahl 2021-08-23 14:00 ` Alan Stern [this message] 2021-08-23 14:00 ` Alan Stern 2021-08-24 6:37 ` [RFC PATCH] USB: host: ehci-atmel: Allow enabling HSIC on SAMA5D2 Alexander Dahl 2021-08-24 6:37 ` Alexander Dahl 2021-08-24 6:45 ` Greg Kroah-Hartman 2021-08-24 6:45 ` Greg Kroah-Hartman 2021-09-02 15:33 ` Nicolas Ferre 2021-09-02 15:33 ` Nicolas Ferre 2021-09-06 7:20 ` Alexander Dahl 2021-09-06 7:20 ` Alexander Dahl
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