From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH v3 07/12] usb: chipidea: add a usb2 driver for ci13xxx Date: Thu, 17 Jul 2014 12:21:56 +0200 Message-ID: <5456516.0fVZeXjF8k@wuerfel> References: <1405499166-6726-1-git-send-email-antoine.tenart@free-electrons.com> <22032517.gk8PRUMaIU@wuerfel> <93903d5fdf85427bb8a418894540c122@BN1PR0301MB0772.namprd03.prod.outlook.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Return-path: In-Reply-To: <93903d5fdf85427bb8a418894540c122-RQSpjbwlmjS6oBnG8T5U3ZwN6zqB+hSMnBOFsp37pqbUKgpGm//BTAC/G2K4zDHf@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org Cc: Peter Chen , "thomas.petazzoni-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org" , "zmxu-eYqpPyKDWXRBDgjK7y7TUQ@public.gmane.org" , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Antoine =?ISO-8859-1?Q?T=E9nart?= , "linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "balbi-l0cyMroinI0@public.gmane.org" , "alexandre.belloni-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org" , "p.zabel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org" , "jszhang-eYqpPyKDWXRBDgjK7y7TUQ@public.gmane.org" , "sebastian.hesselbarth-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org" List-Id: devicetree@vger.kernel.org On Thursday 17 July 2014 01:20:54 Peter Chen wrote: > Thanks, arnd. > > For chipidea generic glue layer case, if there are three devices who use this > driver, and all devices have 32-bit bus, some devices have less 32 address lines. > For example: > > - the device_a doesn't need to use dma_mask > - the device_b needs dma_mask as 0xfffffffff > - the device_c needs dma_mask as 0xfffffff0, assume it has only 28 address lines This makes no sense. You always need a dma mask, so the first case doesn't exist, and the second one is the default. In the third case, I assume you mean 0x0fffffff, which is a 28-bit mask. > My questions are: > - Can we not set dma_mask at driver, and only set dma-ranges at dts for device_b > and device_c as a solution to cover this different dma mask use case? try to understand my earlier reply. What is the problem with device_b? Is that a limitation of the bus it is connected to, or the version of the chipidea hardware? > - If we can't use this solution, would you suggest one? It depends on what the requirement of the hardware is, as I explained now for three times. > - If we can use this solution, for device_b and device_c, how can we write dma-ranges? > I can't find any arm platforms use it, only some powerpc platform use it. > According to the definition from Power_ePAPR_APPROVED_v1.1.pdf, it is > dma-ranges = > but I find the powerpc has different way for using dma-ranges. It's now handled by of_dma_configure() in drivers/of/platform.c for all architectures. Arnd -- 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