Tomi Valkeinen <tomi.valkeinen@xxxxxx> writes:
> Use PM runtime and HWMOD support to handle enabling and disabling of DSS
> modules.
>
> Each DSS module will have get and put functions which can be used to
> enable and disable that module. The functions use pm_runtime and hwmod
> opt-clocks to enable the hardware.
>
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxx>
[...]
> +int dispc_runtime_get(void)
> +{
> + int r;
> +
> + mutex_lock(&dispc.runtime_lock);
It's not clear to me what the lock is trying to protect. I guess it's
the counter? I don't think it should be needed...
> + if (dispc.runtime_count++ == 0) {
You shouldn't need your own use-counting here. The runtime PM core is
already doing usage counting.
Instead, you need to use the ->runtime_suspend() and ->runtime_resume()
callbacks (in dev_pm_ops). These callbacks are called by the runtime PM
core when the usage count goes to/from zero.
IOW, this function should simply be a pm_runtime_get_sync(), and the
rest of the stuff in this function should be done in the
->runtime_resume() callback, which is only executed when the usage_count
transitions from zero.
> + DSSDBG("dispc_runtime_get\n");
> +
> + r = dss_runtime_get();
> + if (r)
> + goto err_dss_get;
> +
> + /* XXX dispc fclk can also come from DSI PLL */
> + clk_enable(dispc.dss_clk);
> +
> + r = pm_runtime_get_sync(&dispc.pdev->dev);
> + WARN_ON(r);
> + if (r < 0)
> + goto err_runtime_get;
> +
> + if (dispc_need_ctx_restore())
> + dispc_restore_context();
> + }
> +
> + mutex_unlock(&dispc.runtime_lock);
> +
> + return 0;
> +
> +err_runtime_get:
> + clk_disable(dispc.dss_clk);
> + dss_runtime_put();
> +err_dss_get:
> + mutex_unlock(&dispc.runtime_lock);
> +
> + return r;
> }
>
> +void dispc_runtime_put(void)
> +{
> + mutex_lock(&dispc.runtime_lock);
> +
> + if (--dispc.runtime_count == 0) {
> + int r;
Same problem here.
No usage counting is required (and probably no locking either.) This
function should simply be a pm_runtime_put(), and the rest of the stuff
should be in the driver's ->runtime_suspend() callback.
> + DSSDBG("dispc_runtime_put\n");
> +
> + dispc_save_context();
> +
> + r = pm_runtime_put_sync(&dispc.pdev->dev);
Does this need to be the _sync() version? It looks like it could be use
the "normal" (async) version.: pm_runtime_put().
> + WARN_ON(r);
> +
> + clk_disable(dispc.dss_clk);
> +
> + dss_runtime_put();
> + }
> +
> + mutex_unlock(&dispc.runtime_lock);
> +}
> +
> +
> bool dispc_go_busy(enum omap_channel channel)
> {
> int bit;
> @@ -530,7 +645,7 @@ void dispc_go(enum omap_channel channel)
> int bit;
> bool enable_bit, go_bit;
>
> - enable_clocks(1);
> + dispc_runtime_get();
Based on the above suggestions, you probably don't need dedicated
functions for this. Just call pm_runtime_get_sync() here...
> if (channel == OMAP_DSS_CHANNEL_LCD ||
> channel == OMAP_DSS_CHANNEL_LCD2)
> @@ -571,7 +686,7 @@ void dispc_go(enum omap_channel channel)
> else
> REG_FLD_MOD(DISPC_CONTROL, 1, bit, bit);
> end:
> - enable_clocks(0);
> + dispc_runtime_put();
...and the pm_runtime_put() here.
Kevin
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