Messages in this thread | | | Subject | Re: [PATCH v5 2/2] memory: ti-emif-sram: introduce relocatable suspend/resume handlers | From | Santosh Shilimkar <> | Date | Mon, 13 Nov 2017 09:07:33 -0800 |
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On 11/10/2017 8:39 AM, Russell King - ARM Linux wrote: > On Mon, Oct 16, 2017 at 08:31:59AM -0700, Santosh Shilimkar wrote: >> Hi Russell, >> >> On 10/13/2017 1:59 PM, Dave Gerlach wrote: >>> Certain SoCs like Texas Instruments AM335x and AM437x require parts >>> of the EMIF PM code to run late in the suspend sequence from SRAM, >>> such as saving and restoring the EMIF context and placing the memory >>> into self-refresh. >>> >>> One requirement for these SoCs to suspend and enter its lowest power >>> mode, called DeepSleep0, is that the PER power domain must be shut off. >>> Because the EMIF (DDR Controller) resides within this power domain, it >>> will lose context during a suspend operation, so we must save it so we >>> can restore once we resume. However, we cannot execute this code from >>> external memory, as it is not available at this point, so the code must >>> be executed late in the suspend path from SRAM. >>> >>> This patch introduces a ti-emif-sram driver that includes several >>> functions written in ARM ASM that are relocatable so the PM SRAM >>> code can use them. It also allocates a region of writable SRAM to >>> be used by the code running in the executable region of SRAM to save >>> and restore the EMIF context. It can export a table containing the >>> absolute addresses of the available PM functions so that other SRAM >>> code can branch to them. This code is required for suspend/resume on >>> AM335x and AM437x to work. >>> >>> In addition to this, to be able to share data structures between C and >>> the ti-emif-sram-pm assembly code, we can automatically generate all of >>> the C struct member offsets and sizes as macros by processing >>> emif-asm-offsets.c into assembly code and then extracting the relevant >>> data as is done for the generated platform asm-offsets.h files. >>> >>> Signed-off-by: Dave Gerlach <d-gerlach@ti.com> >>> --- >>> v4->v5: >>> * Simplify Makefile to generate include/generated/ti-emif-asm-offsets.h >>> >> If you are happy with this version from Dave, can I get your ack please? >> I can add this to the driver-soc then. > > Does it need my ack anymore? It doesn't touch anything in arch/arm. > If you still want it, then... notwithstanding the loss of type checking > that fncpy() gave and the new sram stuff messes up... > > Acked-by: Russell King <rmk+kernel@armlinux.org.uk> > Thanks Russell !!
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