From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sudeep Holla Subject: Re: [PATCH 1/2] tty: amba-pl011: fix earlycon register offsets Date: Tue, 5 Jan 2016 13:45:52 +0000 Message-ID: <568BC910.5050904@arm.com> References: <1450972189-22639-1-git-send-email-timur@codeaurora.org> <20151224164723.GK8644@n2100.arm.linux.org.uk> <20160105123018.GU19062@n2100.arm.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20160105123018.GU19062@n2100.arm.linux.org.uk> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Russell King - ARM Linux Cc: Peter Hurley , Greg Kroah-Hartman , Timur Tabi , andrew.jackson@arm.com, andre.przywara@arm.com, linux-serial@vger.kernel.org, Sudeep Holla , shijie.huang@arm.com, jslaby@suse.com, jun.nie@linaro.org, Linus Walleij , linux-arm-kernel@lists.infradead.org List-Id: linux-serial@vger.kernel.org On 05/01/16 12:30, Russell King - ARM Linux wrote: > On Tue, Jan 05, 2016 at 12:12:31PM +0000, Sudeep Holla wrote: >> Hi Russell, >> >> On Thu, Dec 24, 2015 at 4:47 PM, Russell King - ARM Linux >> wrote: >>> On Thu, Dec 24, 2015 at 09:49:48AM -0600, Timur Tabi wrote: >>>> The REG_x macros are indices into a table, not register offsets. Since >>>> earlycon does not have access to the vendor data, we can currently only >>>> support standard ARM PL011 devices. >>>> >>>> Signed-off-by: Timur Tabi >>> >>> Please credit me with the change; this was obviously a change I made >>> when I posted the updated patches, which Greg had failed to take >>> instead of the original set. Thanks. >>> >> >> I don't see this patch in linux-next. Without this it fails to boot(panics) on >> ARM64 when earlycon is enabled. > [...] > > As far as 4.4 goes, I think it's fate was sealed when Greg took the > wrong set of patches. It's Greg's problem to sort out now. > Since it's boot failure, it should be considered as bug fix and merged. >> Also I think this fix might not be correct >> for ZTE pl011, though it works for ST and standard PL011. > > Yes, earlycon won't work for ZTE PL011. This isn't a big problem at > the moment, because the patch set doesn't wire up the ZTE PL011 itself. Yes, I observed that, but still mentioned it just to check if that was the reason for holding this patch. Thanks for the clarification. > The reason there is that I'm saying no to using a platform device; I > really do not like drivers which end up with multiple different probe > and remove methods. The AMBA PL011 driver is an AMBA primecell driver, > and it sits on the AMBA primecell bus, not the platform bus. > > What I want to see is some way of having the ZTE PL011 appearing on the > AMBA bus, which means we need to come up with some way to deal with > primecells which don't have an ID. That is an open issue, as is how > to deal with earlycon. > Understood and thanks for the detailed explanation. -- Regards, Sudeep From mboxrd@z Thu Jan 1 00:00:00 1970 From: sudeep.holla@arm.com (Sudeep Holla) Date: Tue, 5 Jan 2016 13:45:52 +0000 Subject: [PATCH 1/2] tty: amba-pl011: fix earlycon register offsets In-Reply-To: <20160105123018.GU19062@n2100.arm.linux.org.uk> References: <1450972189-22639-1-git-send-email-timur@codeaurora.org> <20151224164723.GK8644@n2100.arm.linux.org.uk> <20160105123018.GU19062@n2100.arm.linux.org.uk> Message-ID: <568BC910.5050904@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 05/01/16 12:30, Russell King - ARM Linux wrote: > On Tue, Jan 05, 2016 at 12:12:31PM +0000, Sudeep Holla wrote: >> Hi Russell, >> >> On Thu, Dec 24, 2015 at 4:47 PM, Russell King - ARM Linux >> wrote: >>> On Thu, Dec 24, 2015 at 09:49:48AM -0600, Timur Tabi wrote: >>>> The REG_x macros are indices into a table, not register offsets. Since >>>> earlycon does not have access to the vendor data, we can currently only >>>> support standard ARM PL011 devices. >>>> >>>> Signed-off-by: Timur Tabi >>> >>> Please credit me with the change; this was obviously a change I made >>> when I posted the updated patches, which Greg had failed to take >>> instead of the original set. Thanks. >>> >> >> I don't see this patch in linux-next. Without this it fails to boot(panics) on >> ARM64 when earlycon is enabled. > [...] > > As far as 4.4 goes, I think it's fate was sealed when Greg took the > wrong set of patches. It's Greg's problem to sort out now. > Since it's boot failure, it should be considered as bug fix and merged. >> Also I think this fix might not be correct >> for ZTE pl011, though it works for ST and standard PL011. > > Yes, earlycon won't work for ZTE PL011. This isn't a big problem at > the moment, because the patch set doesn't wire up the ZTE PL011 itself. Yes, I observed that, but still mentioned it just to check if that was the reason for holding this patch. Thanks for the clarification. > The reason there is that I'm saying no to using a platform device; I > really do not like drivers which end up with multiple different probe > and remove methods. The AMBA PL011 driver is an AMBA primecell driver, > and it sits on the AMBA primecell bus, not the platform bus. > > What I want to see is some way of having the ZTE PL011 appearing on the > AMBA bus, which means we need to come up with some way to deal with > primecells which don't have an ID. That is an open issue, as is how > to deal with earlycon. > Understood and thanks for the detailed explanation. -- Regards, Sudeep