From mboxrd@z Thu Jan 1 00:00:00 1970 From: sudeep.holla@arm.com (Sudeep Holla) Date: Tue, 25 Aug 2015 14:02:54 +0100 Subject: [PATCH v3 1/1] misc: sram: add dev_pm_ops to support module power gate In-Reply-To: <1438272681-29338-1-git-send-email-shenwei.wang@freescale.com> References: <1438272681-29338-1-git-send-email-shenwei.wang@freescale.com> Message-ID: <55DC677E.1030004@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 30/07/15 17:11, Shenwei Wang wrote: > When system goes into low power states like SUSPEND_MEM and > HIBERNATION, the hardware IP block may be powered off to reduce > the power consumption. This power down will lost all the > data inside the ram. This patch added the dev_pm_ops and > implemented two callbacks: suspend_noirq and resume_noirq, which > will save the data in the on-chip-ram right before power down > and restore it after system resumes. > Who uses this SRAM ? Can't they be released before suspending ? This might not be feasible and time consuming as the size of SRAM increases. Also I just check the entire tree for the users of gen_pool, I found it's used for video/audio and crypto which needs to on-demand basis. Apart from that it's mainly used for low power modes in which case, SRAM needs to be powered on. So can you provide more details on your use-case. > A new property string named "can-power-gate" is added to > the devicetree bindings too. > > Signed-off-by: Shenwei Wang > Signed-off-by: Anson Huang > --- > Change log: > > PATCH v3 > Removed the unnecessary clk_enable/clk_disable. > > PATCH v2 > Use vmalloc to allocate the SRAM backup memory. > Code clean up. > > Documentation/devicetree/bindings/misc/sram.txt | 2 ++ > drivers/misc/sram.c | 42 +++++++++++++++++++++++++ > 2 files changed, 44 insertions(+) > > diff --git a/Documentation/devicetree/bindings/misc/sram.txt b/Documentation/devicetree/bindings/misc/sram.txt > index 36cbe5a..1170086 100644 > --- a/Documentation/devicetree/bindings/misc/sram.txt > +++ b/Documentation/devicetree/bindings/misc/sram.txt > @@ -33,6 +33,8 @@ Optional properties in the area nodes: > > - compatible : standard definition, should contain a vendor specific string > in the form ,[-] > +- can-power-gate: a property to tell the driver that the sram can support > + power gate > Please cc device-tree list for such generic bindings. Regards, Sudeep