From mboxrd@z Thu Jan 1 00:00:00 1970 From: t.figa@samsung.com (Tomasz Figa) Date: Fri, 14 Feb 2014 11:42:50 +0100 Subject: [PATCH v2 4/6] ARM: firmware: add prepare_idle() operation In-Reply-To: <52FDA6B4.6070404@nvidia.com> References: <1391747706-1847-1-git-send-email-acourbot@nvidia.com> <1391747706-1847-5-git-send-email-acourbot@nvidia.com> <52FCA5FC.80504@samsung.com> <52FDA6B4.6070404@nvidia.com> Message-ID: <52FDF32A.1040809@samsung.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 14.02.2014 06:16, Alexandre Courbot wrote: > On 02/13/2014 08:01 PM, Tomasz Figa wrote: >> Hi Alexandre, >> >> On 07.02.2014 05:35, Alexandre Courbot wrote: >>> Some firmwares do not put the CPU into idle mode themselves, but still >>> need to be informed that the CPU is about to enter idle mode before this >>> happens. Add a prepare_idle() operation to the firmware_ops structure to >>> handle such cases. >>> >>> Signed-off-by: Alexandre Courbot >>> --- >>> arch/arm/include/asm/firmware.h | 4 ++++ >>> 1 file changed, 4 insertions(+) >> >> I wonder if .do_idle() couldn't simply return an appropriate error code >> to let the upper layer know that it should proceed with normal CPU idle >> activation, while still letting the firmware know that the CPU is going >> to idle. > > In our particular case I agree it would be enough to use do_idle() to > let the firmware know about the operation and have it return -ENOSYS so > the kernel actually performs it. I'm afraid this might not fulfill all > needs though (e.g. one can imagine a firmware where the OS needs to take > action between the notification and the actual shutdown), and as Stephen > pointed out that would make the name of the function ambiguous at best. > I'd rather keep it the current way for clarity. > OK. I'm not strongly against this, just wanted some more thought on this, so please move on. Best regards, Tomasz