From mboxrd@z Thu Jan 1 00:00:00 1970 From: sudeep.holla@arm.com (Sudeep Holla) Date: Thu, 08 Jan 2015 12:15:35 +0530 Subject: [PATCH RFT 1/2] drivers: bus: check cci device tree node status In-Reply-To: <5487D726.6000603@arm.com> References: <1417186209-5256-1-git-send-email-a.kesavan@samsung.com> <5487C897.9050405@arm.com> <5487D726.6000603@arm.com> Message-ID: <54AE278F.4020003@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Abhilash, On Wednesday 10 December 2014 10:46 AM, Sudeep Holla wrote: > > > On Wednesday 10 December 2014 09:55 AM, Abhilash Kesavan wrote: >> Hi Sudeep, >> >> On Wed, Dec 10, 2014 at 9:44 AM, Sudeep Holla wrote: >>> Hi Abhilash, >>> >>> On Wednesday 10 December 2014 09:31 AM, Abhilash Kesavan wrote: >>>> >>>> Hi, >>>> >>>> On Fri, Nov 28, 2014 at 8:20 PM, Abhilash Kesavan >>>> wrote: >>>>> >>>>> The arm-cci driver completes the probe sequence even if the cci node is >>>>> marked as disabled. Add a check in the driver to honour the cci status >>>>> in the device tree. >>>>> >>>>> Signed-off-by: Abhilash Kesavan >>>> >>>> >>>> This patch helps disable CCI on the Arndale Octa board thus resolving >>>> some imprecise aborts seen on that board. Kindly review. >>>> >>>> Regards, >>>> Abhilash >>>>> >>>>> --- >>>>> drivers/bus/arm-cci.c | 3 +++ >>>>> 1 file changed, 3 insertions(+) >>>>> >>>>> diff --git a/drivers/bus/arm-cci.c b/drivers/bus/arm-cci.c >>>>> index 860da40..0ce5e2d 100644 >>>>> --- a/drivers/bus/arm-cci.c >>>>> +++ b/drivers/bus/arm-cci.c >>>>> @@ -1312,6 +1312,9 @@ static int cci_probe(void) >>>>> if (!np) >>>>> return -ENODEV; >>>>> >>>>> + if (!of_device_is_available(np)) >>>>> + return -ENODEV; >>>>> + >>> >>> >>> IIUC, by this change you are disabling the MCPM boot protocol here. >>> Is there any alternative boot protocol that works on this platform >>> to boot all 8 cores ? Sorry by quick grep couldn't find one, hence >>> so I am asking. >> >> Thanks for the reply. >> On disabling MCPM, we will default to platsmp.c/firmware.c which boots >> 4 cores as per Kevin's comment here[1]. This was the original behavior >> before MCPM was enabled for all 5420 based SoCs. >> > > Thanks for pointing that out. I assume the firmware can handle the > alternate boot protocol and no more workarounds are needed especially > when getting CPUIdle working in this mode. > > Anyways the patch makes sense irrespective how it works on exynos, so > you can add, > > Acked-by: Sudeep Holla > What's the status of this patch. It was useful for me on vexpress for some testing. Please feel free to add Tested-by: Sudeep Holla if this is not yet queued. Regards, Sudeep