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SubjectRe: [PATCH v6 26/30] drm/rockchip: psr: Avoid redundant calls to .set() callback
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On 05.04.2018 11:49, Enric Balletbo i Serra wrote:
> From: Tomasz Figa <tfiga@chromium.org>
>
> The first time after we call rockchip_drm_do_flush() after
> rockchip_drm_psr_register(), we go from PSR_DISABLE to PSR_FLUSH. The
> difference between PSR_DISABLE and PSR_FLUSH is whether or not we have a
> delayed work pending - PSR is off in either state. However
> psr_set_state() only catches the transition from PSR_FLUSH to
> PSR_DISABLE (which never happens), while going from PSR_DISABLE to
> PSR_FLUSH triggers a call to psr->set() to disable PSR while it's
> already disabled. This triggers the eDP PHY power-on sequence without
> being shut down first and this seems to occasionally leave the encoder
> unable to later enable PSR. Let's just simplify the state machine and
> simply consider PSR_DISABLE and PSR_FLUSH the same state. This lets us
> represent the hardware state by a simple boolean called "enabled" and,
> while at it, rename the misleading "active" boolean to "inhibit", which
> represents the purpose much better.

This phrase has no corresponding part in the patch.

>
> Also, userspace can (and does) trigger the rockchip_drm_do_flush() path
> from drmModeDirtyFB() at any time, whether or the encoder is active. If
> no mode is set, we call into analogix_dp_psr_set() which returns -EINVAL
> because encoder->crtc is NULL. Avoid this by starting out with
> psr->allowed set to false.

ditto

>
> Signed-off-by: Kristian H. Kristensen <hoegsberg@chromium.org>
> Signed-off-by: Tomasz Figa <tfiga@chromium.org>

Original author should be first, 1st line of the patch "From:...."
suggests it should be Tomasz.

Regards
Andrzej

> Signed-off-by: Thierry Escande <thierry.escande@collabora.com>
> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
> Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
> ---
>
> drivers/gpu/drm/rockchip/rockchip_drm_psr.c | 79 +++++++++--------------------
> 1 file changed, 23 insertions(+), 56 deletions(-)
>
> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_psr.c b/drivers/gpu/drm/rockchip/rockchip_drm_psr.c
> index c8655e625ba2..448c5fde241c 100644
> --- a/drivers/gpu/drm/rockchip/rockchip_drm_psr.c
> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_psr.c
> @@ -22,19 +22,13 @@
>
> #define PSR_FLUSH_TIMEOUT_MS 100
>
> -enum psr_state {
> - PSR_FLUSH,
> - PSR_ENABLE,
> - PSR_DISABLE,
> -};
> -
> struct psr_drv {
> struct list_head list;
> struct drm_encoder *encoder;
>
> struct mutex lock;
> bool active;
> - enum psr_state state;
> + bool enabled;
>
> struct delayed_work flush_work;
> struct work_struct disable_work;
> @@ -78,52 +72,22 @@ static struct psr_drv *find_psr_by_encoder(struct drm_encoder *encoder)
> return psr;
> }
>
> -static void psr_set_state_locked(struct psr_drv *psr, enum psr_state state)
> +static int psr_set_state_locked(struct psr_drv *psr, bool enable)
> {
> - /*
> - * Allowed finite state machine:
> - *
> - * PSR_ENABLE < = = = = = > PSR_FLUSH
> - * | ^ |
> - * | | |
> - * v | |
> - * PSR_DISABLE < - - - - - - - - -
> - */
> - if (state == psr->state || !psr->active)
> - return;
> -
> - /* Already disabled in flush, change the state, but not the hardware */
> - if (state == PSR_DISABLE && psr->state == PSR_FLUSH) {
> - psr->state = state;
> - return;
> - }
> + int ret;
>
> - /* Actually commit the state change to hardware */
> - switch (state) {
> - case PSR_ENABLE:
> - if (psr->set(psr->encoder, true))
> - return;
> - break;
> -
> - case PSR_DISABLE:
> - case PSR_FLUSH:
> - if (psr->set(psr->encoder, false))
> - return;
> - break;
> -
> - default:
> - pr_err("%s: Unknown state %d\n", __func__, state);
> - return;
> - }
> + if (!psr->active)
> + return -EINVAL;
>
> - psr->state = state;
> -}
> + if (enable == psr->enabled)
> + return 0;
>
> -static void psr_set_state(struct psr_drv *psr, enum psr_state state)
> -{
> - mutex_lock(&psr->lock);
> - psr_set_state_locked(psr, state);
> - mutex_unlock(&psr->lock);
> + ret = psr->set(psr->encoder, enable);
> + if (ret)
> + return ret;
> +
> + psr->enabled = enable;
> + return 0;
> }
>
> static void psr_flush_handler(struct work_struct *work)
> @@ -131,10 +95,8 @@ static void psr_flush_handler(struct work_struct *work)
> struct psr_drv *psr = container_of(to_delayed_work(work),
> struct psr_drv, flush_work);
>
> - /* If the state has changed since we initiated the flush, do nothing */
> mutex_lock(&psr->lock);
> - if (psr->state == PSR_FLUSH)
> - psr_set_state_locked(psr, PSR_ENABLE);
> + psr_set_state_locked(psr, true);
> mutex_unlock(&psr->lock);
> }
>
> @@ -176,6 +138,7 @@ int rockchip_drm_psr_deactivate(struct drm_encoder *encoder)
>
> mutex_lock(&psr->lock);
> psr->active = false;
> + psr->enabled = false;
> mutex_unlock(&psr->lock);
> cancel_delayed_work_sync(&psr->flush_work);
> cancel_work_sync(&psr->disable_work);
> @@ -187,8 +150,12 @@ EXPORT_SYMBOL(rockchip_drm_psr_deactivate);
> static void rockchip_drm_do_flush(struct psr_drv *psr)
> {
> cancel_delayed_work_sync(&psr->flush_work);
> - psr_set_state(psr, PSR_FLUSH);
> - mod_delayed_work(system_wq, &psr->flush_work, PSR_FLUSH_TIMEOUT_MS);
> +
> + mutex_lock(&psr->lock);
> + if (!psr_set_state_locked(psr, false))
> + mod_delayed_work(system_wq, &psr->flush_work,
> + PSR_FLUSH_TIMEOUT_MS);
> + mutex_unlock(&psr->lock);
> }
>
> /**
> @@ -355,8 +322,8 @@ int rockchip_drm_psr_register(struct drm_encoder *encoder,
> INIT_WORK(&psr->disable_work, psr_disable_handler);
> mutex_init(&psr->lock);
>
> - psr->active = true;
> - psr->state = PSR_DISABLE;
> + psr->active = false;
> + psr->enabled = false;
> psr->encoder = encoder;
> psr->set = psr_set;
>


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