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Message-ID: <a3c2c09a881055c43b2fb5394fc99b0372bb3746.camel@mediatek.com>
Date: Thu, 27 Jul 2023 02:55:44 +0000
From: CK Hu (胡俊光) <ck.hu@...iatek.com>
To: "angelogioacchino.delregno@...labora.com"
<angelogioacchino.delregno@...labora.com>,
"chunkuang.hu@...nel.org" <chunkuang.hu@...nel.org>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-mediatek@...ts.infradead.org"
<linux-mediatek@...ts.infradead.org>,
"wenst@...omium.org" <wenst@...omium.org>,
"kernel@...labora.com" <kernel@...labora.com>,
"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
"amergnat@...libre.com" <amergnat@...libre.com>,
"ehristev@...labora.com" <ehristev@...labora.com>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"matthias.bgg@...il.com" <matthias.bgg@...il.com>,
"nfraprado@...labora.com" <nfraprado@...labora.com>
Subject: Re: [PATCH v7 11/11] drm/mediatek: dp: Don't register HPD interrupt
handler for eDP case
Hi, Angelo:
On Tue, 2023-07-25 at 09:32 +0200, AngeloGioacchino Del Regno wrote:
> The interrupt handler for HPD is useful only if a display is actually
> supposed to be hotpluggable, as that manages the machinery to perform
> cable (un)plug detection, debouncing and setup for re-training.
>
> Since eDP panels are not supposed to be hotpluggable we can avoid
> using the HPD interrupts altogether and rely on HPD polling only
> for the suspend/resume case, saving us some spinlocking action and
> the overhead of interrupts firing at every suspend/resume cycle,
> achieving a faster (even if just slightly) display resume.
Reviewed-by: CK Hu <ck.hu@...iatek.com>
>
> Signed-off-by: AngeloGioacchino Del Regno <
> angelogioacchino.delregno@...labora.com>
> Tested-by: Chen-Yu Tsai <wenst@...omium.org>
> Reviewed-by: Alexandre Mergnat <amergnat@...libre.com>
> ---
> drivers/gpu/drm/mediatek/mtk_dp.c | 73 +++++++++++++++++++--------
> ----
> 1 file changed, 46 insertions(+), 27 deletions(-)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c
> b/drivers/gpu/drm/mediatek/mtk_dp.c
> index ba750d463e41..c06fcc7318e7 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dp.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dp.c
> @@ -2182,9 +2182,11 @@ static int mtk_dp_bridge_attach(struct
> drm_bridge *bridge,
>
> mtk_dp->drm_dev = bridge->dev;
>
> - irq_clear_status_flags(mtk_dp->irq, IRQ_NOAUTOEN);
> - enable_irq(mtk_dp->irq);
> - mtk_dp_hwirq_enable(mtk_dp, true);
> + if (mtk_dp->bridge.type != DRM_MODE_CONNECTOR_eDP) {
> + irq_clear_status_flags(mtk_dp->irq, IRQ_NOAUTOEN);
> + enable_irq(mtk_dp->irq);
> + mtk_dp_hwirq_enable(mtk_dp, true);
> + }
>
> return 0;
>
> @@ -2199,8 +2201,10 @@ static void mtk_dp_bridge_detach(struct
> drm_bridge *bridge)
> {
> struct mtk_dp *mtk_dp = mtk_dp_from_bridge(bridge);
>
> - mtk_dp_hwirq_enable(mtk_dp, false);
> - disable_irq(mtk_dp->irq);
> + if (mtk_dp->bridge.type != DRM_MODE_CONNECTOR_eDP) {
> + mtk_dp_hwirq_enable(mtk_dp, false);
> + disable_irq(mtk_dp->irq);
> + }
> mtk_dp->drm_dev = NULL;
> mtk_dp_poweroff(mtk_dp);
> drm_dp_aux_unregister(&mtk_dp->aux);
> @@ -2579,32 +2583,44 @@ static int mtk_dp_probe(struct
> platform_device *pdev)
> mtk_dp->dev = dev;
> mtk_dp->data = (struct mtk_dp_data
> *)of_device_get_match_data(dev);
>
> - mtk_dp->irq = platform_get_irq(pdev, 0);
> - if (mtk_dp->irq < 0)
> - return dev_err_probe(dev, mtk_dp->irq,
> - "failed to request dp irq
> resource\n");
> -
> ret = mtk_dp_dt_parse(mtk_dp, pdev);
> if (ret)
> return dev_err_probe(dev, ret, "Failed to parse dt\n");
>
> + /*
> + * Request the interrupt and install service routine only if we
> are
> + * on full DisplayPort.
> + * For eDP, polling the HPD instead is more convenient because
> we
> + * don't expect any (un)plug events during runtime, hence we
> can
> + * avoid some locking.
> + */
> + if (mtk_dp->data->bridge_type != DRM_MODE_CONNECTOR_eDP) {
> + mtk_dp->irq = platform_get_irq(pdev, 0);
> + if (mtk_dp->irq < 0)
> + return dev_err_probe(dev, mtk_dp->irq,
> + "failed to request dp irq
> resource\n");
> +
> + spin_lock_init(&mtk_dp->irq_thread_lock);
> +
> + irq_set_status_flags(mtk_dp->irq, IRQ_NOAUTOEN);
> + ret = devm_request_threaded_irq(dev, mtk_dp->irq,
> mtk_dp_hpd_event,
> + mtk_dp_hpd_event_thread
> ,
> + IRQ_TYPE_LEVEL_HIGH,
> dev_name(dev),
> + mtk_dp);
> + if (ret)
> + return dev_err_probe(dev, ret,
> + "failed to request
> mediatek dptx irq\n");
> +
> + mtk_dp->need_debounce = true;
> + timer_setup(&mtk_dp->debounce_timer,
> mtk_dp_debounce_timer, 0);
> + }
> +
> mtk_dp->aux.name = "aux_mtk_dp";
> mtk_dp->aux.dev = dev;
> mtk_dp->aux.transfer = mtk_dp_aux_transfer;
> mtk_dp->aux.wait_hpd_asserted = mtk_dp_wait_hpd_asserted;
> drm_dp_aux_init(&mtk_dp->aux);
>
> - spin_lock_init(&mtk_dp->irq_thread_lock);
> -
> - irq_set_status_flags(mtk_dp->irq, IRQ_NOAUTOEN);
> - ret = devm_request_threaded_irq(dev, mtk_dp->irq,
> mtk_dp_hpd_event,
> - mtk_dp_hpd_event_thread,
> - IRQ_TYPE_LEVEL_HIGH,
> dev_name(dev),
> - mtk_dp);
> - if (ret)
> - return dev_err_probe(dev, ret,
> - "failed to request mediatek dptx
> irq\n");
> -
> platform_set_drvdata(pdev, mtk_dp);
>
> if (mtk_dp->data->audio_supported) {
> @@ -2626,9 +2642,6 @@ static int mtk_dp_probe(struct platform_device
> *pdev)
> mtk_dp->bridge.of_node = dev->of_node;
> mtk_dp->bridge.type = mtk_dp->data->bridge_type;
>
> - mtk_dp->need_debounce = true;
> - timer_setup(&mtk_dp->debounce_timer, mtk_dp_debounce_timer, 0);
> -
> if (mtk_dp->bridge.type == DRM_MODE_CONNECTOR_eDP) {
> /*
> * Set the data lanes to idle in case the bootloader
> didn't
> @@ -2639,6 +2652,9 @@ static int mtk_dp_probe(struct platform_device
> *pdev)
> mtk_dp_initialize_aux_settings(mtk_dp);
> mtk_dp_power_enable(mtk_dp);
>
> + /* Disable HW interrupts: we don't need any for eDP */
> + mtk_dp_hwirq_enable(mtk_dp, false);
> +
> /*
> * Power on the AUX to allow reading the EDID from aux-
> bus:
> * please note that it is necessary to call power off
> in the
> @@ -2684,7 +2700,8 @@ static int mtk_dp_remove(struct platform_device
> *pdev)
>
> pm_runtime_put(&pdev->dev);
> pm_runtime_disable(&pdev->dev);
> - del_timer_sync(&mtk_dp->debounce_timer);
> + if (mtk_dp->data->bridge_type != DRM_MODE_CONNECTOR_eDP)
> + del_timer_sync(&mtk_dp->debounce_timer);
> platform_device_unregister(mtk_dp->phy_dev);
> if (mtk_dp->audio_pdev)
> platform_device_unregister(mtk_dp->audio_pdev);
> @@ -2698,7 +2715,8 @@ static int mtk_dp_suspend(struct device *dev)
> struct mtk_dp *mtk_dp = dev_get_drvdata(dev);
>
> mtk_dp_power_disable(mtk_dp);
> - mtk_dp_hwirq_enable(mtk_dp, false);
> + if (mtk_dp->bridge.type != DRM_MODE_CONNECTOR_eDP)
> + mtk_dp_hwirq_enable(mtk_dp, false);
> pm_runtime_put_sync(dev);
>
> return 0;
> @@ -2710,7 +2728,8 @@ static int mtk_dp_resume(struct device *dev)
>
> pm_runtime_get_sync(dev);
> mtk_dp_init_port(mtk_dp);
> - mtk_dp_hwirq_enable(mtk_dp, true);
> + if (mtk_dp->bridge.type != DRM_MODE_CONNECTOR_eDP)
> + mtk_dp_hwirq_enable(mtk_dp, true);
> mtk_dp_power_enable(mtk_dp);
>
> return 0;
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