lkml.org 
[lkml]   [2018]   [Apr]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 01/14] memory: ti-emif-sram: Add resume function to recopy sram code
From
Date
On 4/11/18 9:53 PM, Keerthy wrote:
> From: Dave Gerlach <d-gerlach@ti.com>
>
> After an RTC+DDR cycle we lose sram context so emif pm functions present
> in sram are lost. We can check if the first byte of the original
> code in DDR contains the same first byte as the code in sram, and if
> they do not match we know we have lost context and must recopy the
> functions to the previous address to maintain PM functionality.
>
> Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
> Signed-off-by: Keerthy <j-keerthy@ti.com>
> ---
> drivers/memory/ti-emif-pm.c | 24 ++++++++++++++++++++++++
> 1 file changed, 24 insertions(+)
>
> diff --git a/drivers/memory/ti-emif-pm.c b/drivers/memory/ti-emif-pm.c
> index 632651f..ec4a62c 100644
> --- a/drivers/memory/ti-emif-pm.c
> +++ b/drivers/memory/ti-emif-pm.c
> @@ -249,6 +249,25 @@ int ti_emif_get_mem_type(void)
> };
> MODULE_DEVICE_TABLE(of, ti_emif_of_match);
>
> +#ifdef CONFIG_PM_SLEEP
> +static int ti_emif_resume(struct device *dev)
> +{
> + unsigned long tmp =
> + __raw_readl((void *)emif_instance->ti_emif_sram_virt);
> +
> + /*
> + * Check to see if what we are copying is already present in the
> + * first byte at the destination, only copy if it is not which
> + * indicates we have lost context and sram no longer contains
> + * the PM code
> + */

> + if (tmp != ti_emif_sram)
> + ti_emif_push_sram(dev, emif_instance);
> +
> + return 0;
> +}
> +#endif /* CONFIG_PM_SLEEP */
Instead of this indirect method , why can't just check the previous
deep sleep mode and based on that do copy or not. EMIF power status
register should have something like that ?

Another minor point is even though there is nothing to do in suspend,
might be good to have a callback with comment that nothing to do with
some explanation why not. Don't have strong preference but may for
better readability.

Regards,
Santosh


\
 
 \ /
  Last update: 2018-04-12 18:44    [W:0.172 / U:0.028 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site