On Monday 16 January 2012 08:23 PM, [email protected] wrote:
> ext Shubhrajyoti wrote on 2012-01-16:
>> On Monday 16 January 2012 06:41 PM, [email protected] wrote:
>>> ext Shubhrajyoti D wrote on 2012-01-16:
>>>> The commit 11dd62:[omap_hsmmc: context save/restore support]
>>>>
>>>> does a reset and restores AUTOIDLE settings.
>>>> This patch saves the register does a reset and restores
>>>> the same configuration.
>>> ...
>>>> if (pdata->get_context_loss_count) {
>>>> @@ -700,6 +700,7 @@ static int omap_hsmmc_context_restore(struct
>>>> omap_hsmmc_host *host)
>>>> && time_before(jiffies, timeout)) ; + sysc =
>>>> OMAP_HSMMC_READ(host->base, SYSCONFIG); /* Do software reset */
>>>> OMAP_HSMMC_WRITE(host->base, SYSCONFIG, SOFTRESET); timeout =
>>>> jiffies + msecs_to_jiffies(MMC_TIMEOUT_MS);
>>>> @@ -707,8 +708,7 @@ static int omap_hsmmc_context_restore(struct
>>>> omap_hsmmc_host *host)
>>>> && time_before(jiffies, timeout))
>>>> ;
>>>> - OMAP_HSMMC_WRITE(host->base, SYSCONFIG,
>>>> - OMAP_HSMMC_READ(host->base, SYSCONFIG) | AUTOIDLE);
>>>> + OMAP_HSMMC_WRITE(host->base, SYSCONFIG, sysc);
>>> The meaning of the code is to restore the register context after it was lost
>> during transition into low power consumption state. SW reset is needed to
>> bring
>> all the registers in a consistent state before reconfiguring some of them.
>> Agreed thanks.
>>> Saving and restoring the SYSCONFIG register across SW reset is not needed.
>>>
>>> Also re-configuring AUTOIDLE feature is not necessary since SYSCONFIG reset
>> value has is 1 already, according to TRM. I guess it was done to make things
>> more explicit.
>> However in addition to autoidle there are other bits in the register
>> like the sidle mode , enable wakeup which will get not get overwritten now.
>>
>> Do you agree?
> No, there's no need to do that - after SW reset the registers have predefined
> reset values; the reset value is correct in case of SYSCONFIG register for
> most of omap3|4 boards based, doesn't need any update after SW reset.
>
> If in case of your board the reset value of SYSCONFIG register is not what
> you want - you still cannot rely on the contents of the SYSCONFIG register
> once the context was lost, i.e. saving its value before SW reset doesn't
> help.
> You would need to initialize it to the proper value after the SW reset
> manually, probably the same value that you used during initialization.
if you check the following code
arch/arm/mach-omap2/omap_hwmod_44xx_data.c
/*
* 'mmc' class
* multimedia card high-speed/sd/sdio (mmc/sd/sdio) host controller
*/
static struct omap_hwmod_class_sysconfig omap44xx_mmc_sysc = {
.rev_offs = 0x0000,
.sysc_offs = 0x0010,
.sysc_flags = (SYSC_HAS_EMUFREE | SYSC_HAS_MIDLEMODE |
SYSC_HAS_RESET_STATUS | SYSC_HAS_SIDLEMODE |
SYSC_HAS_SOFTRESET),
.idlemodes = (SIDLE_FORCE | SIDLE_NO | SIDLE_SMART |
SIDLE_SMART_WKUP | MSTANDBY_FORCE | MSTANDBY_NO |
MSTANDBY_SMART | MSTANDBY_SMART_WKUP),
.sysc_fields = &omap_hwmod_sysc_type2,
<>
arch/arm/mach-omap2/omap_hwmod.c
* upon error or 0 upon success.
*/
static int _enable_wakeup(struct omap_hwmod *oh, u32 *v)
{
if (!oh->class->sysc ||
!((oh->class->sysc->sysc_flags & SYSC_HAS_ENAWAKEUP) ||
(oh->class->sysc->idlemodes & SIDLE_SMART_WKUP) ||
(oh->class->sysc->idlemodes & MSTANDBY_SMART_WKUP)))
return -EINVAL;
if (!oh->class->sysc->sysc_fields) {
WARN(1, "omap_hwmod: %s: offset struct for sysconfig not
provided in class\n", oh->name);
return -EINVAL;
}
if (oh->class->sysc->sysc_flags & SYSC_HAS_ENAWAKEUP)
*v |= 0x1 << oh->class->sysc->sysc_fields->enwkup_shift;
if (oh->class->sysc->idlemodes & SIDLE_SMART_WKUP)
_set_slave_idlemode(oh, HWMOD_IDLEMODE_SMART_WKUP, v);
if (oh->class->sysc->idlemodes & MSTANDBY_SMART_WKUP)
_set_master_standbymode(oh, HWMOD_IDLEMODE_SMART_WKUP, v);
however, I agree we could use hwmod framework to reset.
> Denis
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