Re: [PATCH v2] ARM: OMAP2+: hwmod: Add a new state to handle hwmods left enabled at init

Govindraj
2011-11-21T10:03:35Z

Hi Rajendra,

On Mon, Nov 21, 2011 at 11:45 AM, Rajendra Nayak <rnayak@ti.com> wrote:
> An hwmod with a 'HWMOD_INIT_NO_IDLE' flag set, is left in
> enabled state by the hwmod framework post the initial setup.
> Once a real user of the device (a driver) tries to enable it
> at a later point, the hwmod framework throws a WARN() about
> the device being already in enabled state.
>
> Fix this by introducing a new state '_HWMOD_STATE_ENABLED_AT_INIT'
> to identify such devices/hwmods, so nothing but just a state
> change to '_HWMOD_STATE_ENABLED' can be done when the device/hwmod
> is requested to be enabled (the first time) by its driver/user.
>
> A good example of a such a device is an UART used as debug console.
> The UART module needs to be kept enabled through the boot, until the
> UART driver takes control of it, for debug prints to appear on
> the console.
>
> Acked-by: Kevin Hilman <khilman@ti.com>
> Acked-by: Benoit Cousson <b-cousson@ti.com>
> Signed-off-by: Rajendra Nayak <rnayak@ti.com>
> ---
> changes in v2:
> Fixed minor typos, removed stay change, updated comment
> in header.
>
>  arch/arm/mach-omap2/omap_hwmod.c             |   15 ++++++++++++++-
>  arch/arm/plat-omap/include/plat/omap_hwmod.h |    6 ++++++
>  2 files changed, 20 insertions(+), 1 deletions(-)
>
> diff --git a/arch/arm/mach-omap2/omap_hwmod.c b/arch/arm/mach-omap2/omap_hwmod.c
> index 6b3088d..72ee723 100644
> --- a/arch/arm/mach-omap2/omap_hwmod.c
> +++ b/arch/arm/mach-omap2/omap_hwmod.c
> @@ -1441,6 +1441,17 @@ static int _enable(struct omap_hwmod *oh)
>
>        pr_debug("omap_hwmod: %s: enabling\n", oh->name);
>
> +       /*
> +        * hwmods' with HWMOD_INIT_NO_IDLE flag set, are left
> +        * in enabled state at init.
> +        * Now that someone is really trying to enable them,
> +        * just update the state.
> +        */
> +       if (oh->_state == _HWMOD_STATE_ENABLED_AT_INIT) {
> +               oh->_state = _HWMOD_STATE_ENABLED;
> +               return 0;
> +       }
> +

one issue returning from here without doing
omap_hwmod_mux(oh->mux, _HWMOD_STATE_ENABLED);

causes hmux->enabled to be false after first _enable (get_sync)

and for first _idle(put/put_sync)

omap_hwmod_mux(oh->mux, _HWMOD_STATE_IDLE);
will not happen and will not enable rx_pad wake-up for uart.
so this is causing wake-up failures from off mode.

[code_snip]

void omap_hwmod_mux(struct omap_hwmod_mux_info *hmux, u8 state)
{
int i;

/* Runtime idling of dynamic pads */
if (state == _HWMOD_STATE_IDLE && hmux->enabled) {
for (i = 0; i < hmux->nr_pads_dynamic; i++) {
struct omap_device_pad *pad = hmux->pads_dynamic[i];
int val = -EINVAL;

val = pad->idle;
omap_mux_write(pad->partition, val,
pad->mux->reg_offset);
}

return;
}

[..]

if (state == _HWMOD_STATE_ENABLED)
hmux->enabled = true;
else
hmux->enabled = false;
}

[..]

--
Thanks,
Govindraj.R
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