Messages in this thread | | | Date | Mon, 30 Jan 2023 09:58:51 -0800 | Subject | Re: [PATCH v2 2/2] drm/msm/dp: Return IRQ_NONE for unhandled interrupts | From | Kuogee Hsieh <> |
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On 1/26/2023 5:09 PM, Douglas Anderson wrote: > If our interrupt handler gets called and we don't really handle the > interrupt then we should return IRQ_NONE. The current interrupt > handler didn't do this, so let's fix it. > > NOTE: for some of the cases it's clear that we should return IRQ_NONE > and some cases it's clear that we should return IRQ_HANDLED. However, > there are a few that fall somewhere in between. Specifically, the > documentation for when to return IRQ_NONE vs. IRQ_HANDLED is probably > best spelled out in the commit message of commit d9e4ad5badf4 > ("Document that IRQ_NONE should be returned when IRQ not actually > handled"). That commit makes it clear that we should return > IRQ_HANDLED if we've done something to make the interrupt stop > happening. > > The case where it's unclear is, for instance, in dp_aux_isr() after > we've read the interrupt using dp_catalog_aux_get_irq() and confirmed > that "isr" is non-zero. The function dp_catalog_aux_get_irq() not only > reads the interrupts but it also "ack"s all the interrupts that are > returned. For an "unknown" interrupt this has a very good chance of > actually stopping the interrupt from happening. That would mean we've > identified that it's our device and done something to stop them from > happening and should return IRQ_HANDLED. Specifically, it should be > noted that most interrupts that need "ack"ing are ones that are > one-time events and doing an "ack" is enough to clear them. However, > since these interrupts are unknown then, by definition, it's unknown > if "ack"ing them is truly enough to clear them. It's possible that we > also need to remove the original source of the interrupt. In this > case, IRQ_NONE would be a better choice. > > Given that returning an occasional IRQ_NONE isn't the absolute end of > the world, however, let's choose that course of action. The IRQ > framework will forgive a few IRQ_NONE returns now and again (and it > won't even log them, which is why we have to log them ourselves). This > means that if we _do_ end hitting an interrupt where "ack"ing isn't > enough the kernel will eventually detect the problem and shut our > device down. > > Signed-off-by: Douglas Anderson <dianders@chromium.org> Tested-by: Kuogee Hsieh <quic_khsieh@quicinc.com> Reviewed-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
> --- > > (no changes since v1) > > drivers/gpu/drm/msm/dp/dp_aux.c | 12 +++++++----- > drivers/gpu/drm/msm/dp/dp_aux.h | 2 +- > drivers/gpu/drm/msm/dp/dp_ctrl.c | 10 ++++++++-- > drivers/gpu/drm/msm/dp/dp_ctrl.h | 2 +- > drivers/gpu/drm/msm/dp/dp_display.c | 8 +++++--- > 5 files changed, 22 insertions(+), 12 deletions(-) > > diff --git a/drivers/gpu/drm/msm/dp/dp_aux.c b/drivers/gpu/drm/msm/dp/dp_aux.c > index 84f9e3e5f964..8e3b677f35e6 100644 > --- a/drivers/gpu/drm/msm/dp/dp_aux.c > +++ b/drivers/gpu/drm/msm/dp/dp_aux.c > @@ -368,14 +368,14 @@ static ssize_t dp_aux_transfer(struct drm_dp_aux *dp_aux, > return ret; > } > > -void dp_aux_isr(struct drm_dp_aux *dp_aux) > +irqreturn_t dp_aux_isr(struct drm_dp_aux *dp_aux) > { > u32 isr; > struct dp_aux_private *aux; > > if (!dp_aux) { > DRM_ERROR("invalid input\n"); > - return; > + return IRQ_NONE; > } > > aux = container_of(dp_aux, struct dp_aux_private, dp_aux); > @@ -384,11 +384,11 @@ void dp_aux_isr(struct drm_dp_aux *dp_aux) > > /* no interrupts pending, return immediately */ > if (!isr) > - return; > + return IRQ_NONE; > > if (!aux->cmd_busy) { > DRM_ERROR("Unexpected DP AUX IRQ %#010x when not busy\n", isr); > - return; > + return IRQ_NONE; > } > > /* > @@ -420,10 +420,12 @@ void dp_aux_isr(struct drm_dp_aux *dp_aux) > aux->aux_error_num = DP_AUX_ERR_NONE; > } else { > DRM_WARN("Unexpected interrupt: %#010x\n", isr); > - return; > + return IRQ_NONE; > } > > complete(&aux->comp); > + > + return IRQ_HANDLED; > } > > void dp_aux_reconfig(struct drm_dp_aux *dp_aux) > diff --git a/drivers/gpu/drm/msm/dp/dp_aux.h b/drivers/gpu/drm/msm/dp/dp_aux.h > index e930974bcb5b..511305da4f66 100644 > --- a/drivers/gpu/drm/msm/dp/dp_aux.h > +++ b/drivers/gpu/drm/msm/dp/dp_aux.h > @@ -11,7 +11,7 @@ > > int dp_aux_register(struct drm_dp_aux *dp_aux); > void dp_aux_unregister(struct drm_dp_aux *dp_aux); > -void dp_aux_isr(struct drm_dp_aux *dp_aux); > +irqreturn_t dp_aux_isr(struct drm_dp_aux *dp_aux); > void dp_aux_init(struct drm_dp_aux *dp_aux); > void dp_aux_deinit(struct drm_dp_aux *dp_aux); > void dp_aux_reconfig(struct drm_dp_aux *dp_aux); > diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c > index dd26ca651a05..1a5377ef1967 100644 > --- a/drivers/gpu/drm/msm/dp/dp_ctrl.c > +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c > @@ -1979,27 +1979,33 @@ int dp_ctrl_off(struct dp_ctrl *dp_ctrl) > return ret; > } > > -void dp_ctrl_isr(struct dp_ctrl *dp_ctrl) > +irqreturn_t dp_ctrl_isr(struct dp_ctrl *dp_ctrl) > { > struct dp_ctrl_private *ctrl; > u32 isr; > + irqreturn_t ret = IRQ_NONE; > > if (!dp_ctrl) > - return; > + return IRQ_NONE; > > ctrl = container_of(dp_ctrl, struct dp_ctrl_private, dp_ctrl); > > isr = dp_catalog_ctrl_get_interrupt(ctrl->catalog); > > + > if (isr & DP_CTRL_INTR_READY_FOR_VIDEO) { > drm_dbg_dp(ctrl->drm_dev, "dp_video_ready\n"); > complete(&ctrl->video_comp); > + ret = IRQ_HANDLED; > } > > if (isr & DP_CTRL_INTR_IDLE_PATTERN_SENT) { > drm_dbg_dp(ctrl->drm_dev, "idle_patterns_sent\n"); > complete(&ctrl->idle_comp); > + ret = IRQ_HANDLED; > } > + > + return ret; > } > > struct dp_ctrl *dp_ctrl_get(struct device *dev, struct dp_link *link, > diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.h b/drivers/gpu/drm/msm/dp/dp_ctrl.h > index 9f29734af81c..c3af06dc87b1 100644 > --- a/drivers/gpu/drm/msm/dp/dp_ctrl.h > +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.h > @@ -25,7 +25,7 @@ int dp_ctrl_off_link_stream(struct dp_ctrl *dp_ctrl); > int dp_ctrl_off_link(struct dp_ctrl *dp_ctrl); > int dp_ctrl_off(struct dp_ctrl *dp_ctrl); > void dp_ctrl_push_idle(struct dp_ctrl *dp_ctrl); > -void dp_ctrl_isr(struct dp_ctrl *dp_ctrl); > +irqreturn_t dp_ctrl_isr(struct dp_ctrl *dp_ctrl); > void dp_ctrl_handle_sink_request(struct dp_ctrl *dp_ctrl); > struct dp_ctrl *dp_ctrl_get(struct device *dev, struct dp_link *link, > struct dp_panel *panel, struct drm_dp_aux *aux, > diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c > index bde1a7ce442f..b5343c9f1c1e 100644 > --- a/drivers/gpu/drm/msm/dp/dp_display.c > +++ b/drivers/gpu/drm/msm/dp/dp_display.c > @@ -1204,7 +1204,7 @@ static int dp_hpd_event_thread_start(struct dp_display_private *dp_priv) > static irqreturn_t dp_display_irq_handler(int irq, void *dev_id) > { > struct dp_display_private *dp = dev_id; > - irqreturn_t ret = IRQ_HANDLED; > + irqreturn_t ret = IRQ_NONE; > u32 hpd_isr_status; > > if (!dp) { > @@ -1232,13 +1232,15 @@ static irqreturn_t dp_display_irq_handler(int irq, void *dev_id) > > if (hpd_isr_status & DP_DP_HPD_UNPLUG_INT_MASK) > dp_add_event(dp, EV_HPD_UNPLUG_INT, 0, 0); > + > + ret = IRQ_HANDLED; > } > > /* DP controller isr */ > - dp_ctrl_isr(dp->ctrl); > + ret |= dp_ctrl_isr(dp->ctrl); > > /* DP aux isr */ > - dp_aux_isr(dp->aux); > + ret |= dp_aux_isr(dp->aux); > > return ret; > }
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