Messages in this thread | | | Subject | Re: [PATCH] drm/stm: ltdc: improve pm_runtime to stop clocks | From | yannick Fertre <> | Date | Tue, 6 Jul 2021 17:21:03 +0200 |
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Hi Raphaël,
thanks for the patch.
Tested-by: Yannick Fertre <yannick.fertre@foss.st.com>
On 6/29/21 1:58 PM, Raphael GALLAIS-POU - foss wrote: > Bugzilla ticket: https://intbugzilla.st.com/show_bug.cgi?id=60620 > Gerrit patch: https://gerrit.st.com/c/mpu/oe/st/linux-stm32/+/208093/ > > In the LTDC driver, pm_runtime_get_sync was wrongly used and caused the > LTDC pixel clock to be systematically enabled in the clock summary. > > After one simple use of the LTDC by activating and deactivating, > the clock summary results as below: > > ~# cat /sys/kernel/debug/clk/clk_summary | grep ltdc > ltdc_px 1 1 0 29700000 0 0 50000 N > ltdc 0 0 0 133250000 0 0 50000 N > > By doing so, pm_runtime_get_sync only increments the clock counter when > the driver was in not active, displaying the right information when the > LTDC is not in use, resulting of the below clock summary after deactivation > of the LTDC. > > ~# cat /sys/kernel/debug/clk/clk_summary | grep ltdc > ltdc_px 0 0 0 29700000 0 0 50000 N > ltdc 0 0 0 133250000 0 0 50000 N > > The clocks are activated either by the crtc_set_nofb function or > by the crtc_atomic_enable function. A check of pm_runtime activity must > be done before set clocks on. This check must also be done for others > functions which access registers. > > Signed-off-by: Raphael Gallais-Pou <raphael.gallais-pou@foss.st.com> > --- > drivers/gpu/drm/stm/ltdc.c | 21 ++++++++++++++++++++- > 1 file changed, 20 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c > index 08b71248044d..bf9d18023698 100644 > --- a/drivers/gpu/drm/stm/ltdc.c > +++ b/drivers/gpu/drm/stm/ltdc.c > @@ -425,10 +425,17 @@ static void ltdc_crtc_atomic_enable(struct drm_crtc *crtc, > { > struct ltdc_device *ldev = crtc_to_ltdc(crtc); > struct drm_device *ddev = crtc->dev; > + int ret; > > DRM_DEBUG_DRIVER("\n"); > > - pm_runtime_get_sync(ddev->dev); > + if (!pm_runtime_active(ddev->dev)) { > + ret = pm_runtime_get_sync(ddev->dev); > + if (ret) { > + DRM_ERROR("Failed to set mode, cannot get sync\n"); > + return; > + } > + } > > /* Sets the background color value */ > reg_write(ldev->regs, LTDC_BCCR, BCCR_BCBLACK); > @@ -783,6 +790,7 @@ static void ltdc_plane_atomic_update(struct drm_plane *plane, > struct drm_plane_state *newstate = drm_atomic_get_new_plane_state(state, > plane); > struct drm_framebuffer *fb = newstate->fb; > + struct drm_device *ddev = plane->dev; > u32 lofs = plane->index * LAY_OFS; > u32 x0 = newstate->crtc_x; > u32 x1 = newstate->crtc_x + newstate->crtc_w - 1; > @@ -792,6 +800,11 @@ static void ltdc_plane_atomic_update(struct drm_plane *plane, > u32 val, pitch_in_bytes, line_length, paddr, ahbp, avbp, bpcr; > enum ltdc_pix_fmt pf; > > + if (!pm_runtime_active(ddev->dev)) { > + DRM_DEBUG_DRIVER("crtc not activated"); > + return; > + } > + > if (!newstate->crtc || !fb) { > DRM_DEBUG_DRIVER("fb or crtc NULL"); > return; > @@ -897,8 +910,14 @@ static void ltdc_plane_atomic_disable(struct drm_plane *plane, > struct drm_plane_state *oldstate = drm_atomic_get_old_plane_state(state, > plane); > struct ltdc_device *ldev = plane_to_ltdc(plane); > + struct drm_device *ddev = plane->dev; > u32 lofs = plane->index * LAY_OFS; > > + if (!pm_runtime_active(ddev->dev)) { > + DRM_DEBUG_DRIVER("crtc already deactivated"); > + return; > + } > + > /* disable layer */ > reg_clear(ldev->regs, LTDC_L1CR + lofs, LXCR_LEN); > >
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