* Re: [PATCH v3 3/3] drm/bridge: ti-sn65dsi86: Support hotplug detection
2022-03-10 15:22 ` [PATCH v3 3/3] drm/bridge: ti-sn65dsi86: Support hotplug detection Kieran Bingham
@ 2022-03-10 15:26 ` Kieran Bingham
2022-03-10 16:42 ` Laurent Pinchart
2022-03-10 23:10 ` Doug Anderson
2 siblings, 0 replies; 16+ messages in thread
From: Kieran Bingham @ 2022-03-10 15:26 UTC (permalink / raw)
To: Douglas Anderson, Sam Ravnborg, dri-devel, linux-kernel,
linux-renesas-soc
Cc: Andrzej Hajda, Neil Armstrong, Robert Foss, Laurent Pinchart,
Jonas Karlman, Jernej Skrabec, David Airlie, Daniel Vetter,
Laurent Pinchart
Quoting Kieran Bingham (2022-03-10 15:22:27)
> When the SN65DSI86 is used in DisplayPort mode, its output is likely
> routed to a DisplayPort connector, which can benefit from hotplug
> detection. Support it in such cases, with polling mode only for now.
>
> The implementation is limited to the bridge operations, as the connector
> operations are legacy and new users should use
> DRM_BRIDGE_ATTACH_NO_CONNECTOR.
>
> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
> ---
> Changes since v1:
>
> - Document the no_hpd field
> - Rely on the SN_HPD_DISABLE_REG default value in the HPD case
> - Add a TODO comment regarding IRQ support
> [Kieran]
> - Fix spelling s/assrted/asserted/
> - Only enable HPD on DisplayPort connector.
> - Support IRQ based hotplug detect
>
> Changes since v2: [Kieran]
> - Use unsigned int for values read by regmap
> - Update HPD support warning message
> - Only enable OP_HPD if IRQ support enabled.
> - Only register IRQ handler during ti_sn_bridge_probe()
> - Store IRQ in the struct ti_sn65dsi86
> - Register IRQ only when !no-hpd
> - Refactor DRM_BRIDGE_OP_DETECT and DRM_BRIDGE_OP_HPD handling
>
> drivers/gpu/drm/bridge/ti-sn65dsi86.c | 142 +++++++++++++++++++++++---
> 1 file changed, 129 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> index d581c820e5d8..328a48f09f97 100644
> --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> @@ -70,6 +70,7 @@
> #define BPP_18_RGB BIT(0)
> #define SN_HPD_DISABLE_REG 0x5C
> #define HPD_DISABLE BIT(0)
> +#define HPD_DEBOUNCED_STATE BIT(4)
> #define SN_GPIO_IO_REG 0x5E
> #define SN_GPIO_INPUT_SHIFT 4
> #define SN_GPIO_OUTPUT_SHIFT 0
> @@ -106,10 +107,24 @@
> #define SN_PWM_EN_INV_REG 0xA5
> #define SN_PWM_INV_MASK BIT(0)
> #define SN_PWM_EN_MASK BIT(1)
> +#define SN_IRQ_EN_REG 0xE0
> +#define IRQ_EN BIT(0)
> +#define SN_IRQ_HPD_REG 0xE6
> +#define IRQ_HPD_EN BIT(0)
> +#define IRQ_HPD_INSERTION_EN BIT(1)
> +#define IRQ_HPD_REMOVAL_EN BIT(2)
> +#define IRQ_HPD_REPLUG_EN BIT(3)
> +#define IRQ_HPD_PLL_UNLOCK_EN BIT(5)
> #define SN_AUX_CMD_STATUS_REG 0xF4
> #define AUX_IRQ_STATUS_AUX_RPLY_TOUT BIT(3)
> #define AUX_IRQ_STATUS_AUX_SHORT BIT(5)
> #define AUX_IRQ_STATUS_NAT_I2C_FAIL BIT(6)
> +#define SN_IRQ_HPD_STATUS_REG 0xF5
> +#define IRQ_HPD_STATUS BIT(0)
> +#define IRQ_HPD_INSERTION_STATUS BIT(1)
> +#define IRQ_HPD_REMOVAL_STATUS BIT(2)
> +#define IRQ_HPD_REPLUG_STATUS BIT(3)
> +#define IRQ_PLL_UNLOCK BIT(5)
>
> #define MIN_DSI_CLK_FREQ_MHZ 40
>
> @@ -168,6 +183,12 @@
> * @pwm_enabled: Used to track if the PWM signal is currently enabled.
> * @pwm_pin_busy: Track if GPIO4 is currently requested for GPIO or PWM.
> * @pwm_refclk_freq: Cache for the reference clock input to the PWM.
> + *
> + * @no_hpd: Disable hot-plug detection as instructed by device tree (used
> + * for instance for eDP panels whose HPD signal won't be asserted
> + * until the panel is turned on, and is thus not usable for
> + * downstream device detection).
> + * @irq: IRQ number for the device.
> */
> struct ti_sn65dsi86 {
> struct auxiliary_device bridge_aux;
> @@ -202,6 +223,9 @@ struct ti_sn65dsi86 {
> atomic_t pwm_pin_busy;
> #endif
> unsigned int pwm_refclk_freq;
> +
> + bool no_hpd;
> + int irq;
> };
>
> static const struct regmap_range ti_sn65dsi86_volatile_ranges[] = {
> @@ -316,23 +340,25 @@ static void ti_sn65dsi86_enable_comms(struct ti_sn65dsi86 *pdata)
> ti_sn_bridge_set_refclk_freq(pdata);
>
> /*
> - * HPD on this bridge chip is a bit useless. This is an eDP bridge
> - * so the HPD is an internal signal that's only there to signal that
> - * the panel is done powering up. ...but the bridge chip debounces
> - * this signal by between 100 ms and 400 ms (depending on process,
> - * voltage, and temperate--I measured it at about 200 ms). One
> + * As this is an eDP bridge, the output will be connected to a fixed
> + * panel in most systems. HPD is in that case only an internal signal
> + * to signal that the panel is done powering up. The bridge chip
> + * debounces this signal by between 100 ms and 400 ms (depending on
> + * process, voltage, and temperate--I measured it at about 200 ms). One
> * particular panel asserted HPD 84 ms after it was powered on meaning
> * that we saw HPD 284 ms after power on. ...but the same panel said
> * that instead of looking at HPD you could just hardcode a delay of
> - * 200 ms. We'll assume that the panel driver will have the hardcoded
> - * delay in its prepare and always disable HPD.
> + * 200 ms. HPD is thus a bit useless. For this type of use cases, we'll
> + * assume that the panel driver will have the hardcoded delay in its
> + * prepare and always disable HPD.
> *
> - * If HPD somehow makes sense on some future panel we'll have to
> - * change this to be conditional on someone specifying that HPD should
> - * be used.
> + * However, on some systems, the output is connected to a DisplayPort
> + * connector. HPD is needed in such cases. To accommodate both use
> + * cases, enable HPD only when requested.
> */
> - regmap_update_bits(pdata->regmap, SN_HPD_DISABLE_REG, HPD_DISABLE,
> - HPD_DISABLE);
> + if (pdata->no_hpd)
> + regmap_update_bits(pdata->regmap, SN_HPD_DISABLE_REG,
> + HPD_DISABLE, HPD_DISABLE);
>
> pdata->comms_enabled = true;
>
> @@ -1135,6 +1161,36 @@ static void ti_sn_bridge_atomic_post_disable(struct drm_bridge *bridge,
> pm_runtime_put_sync(pdata->dev);
> }
>
> +static enum drm_connector_status ti_sn_bridge_detect(struct drm_bridge *bridge)
> +{
> + struct ti_sn65dsi86 *pdata = bridge_to_ti_sn65dsi86(bridge);
> + int val;
> +
> + regmap_read(pdata->regmap, SN_HPD_DISABLE_REG, &val);
> +
> + return val & HPD_DEBOUNCED_STATE ? connector_status_connected
> + : connector_status_disconnected;
> +}
> +
> +static void ti_sn_bridge_hpd_enable(struct drm_bridge *bridge)
> +{
> + struct ti_sn65dsi86 *pdata = bridge_to_ti_sn65dsi86(bridge);
> +
> + /* The device must remain active for HPD to function */
> + pm_runtime_get_sync(pdata->dev);
> + regmap_write(pdata->regmap, SN_IRQ_HPD_REG,
> + IRQ_HPD_EN | IRQ_HPD_INSERTION_EN |
> + IRQ_HPD_REMOVAL_EN | IRQ_HPD_REPLUG_EN);
> +}
> +
> +static void ti_sn_bridge_hpd_disable(struct drm_bridge *bridge)
> +{
> + struct ti_sn65dsi86 *pdata = bridge_to_ti_sn65dsi86(bridge);
> +
> + regmap_write(pdata->regmap, SN_IRQ_HPD_REG, 0);
> + pm_runtime_put_autosuspend(pdata->dev);
> +}
> +
> static struct edid *ti_sn_bridge_get_edid(struct drm_bridge *bridge,
> struct drm_connector *connector)
> {
> @@ -1153,6 +1209,9 @@ static const struct drm_bridge_funcs ti_sn_bridge_funcs = {
> .detach = ti_sn_bridge_detach,
> .mode_valid = ti_sn_bridge_mode_valid,
> .get_edid = ti_sn_bridge_get_edid,
> + .detect = ti_sn_bridge_detect,
> + .hpd_enable = ti_sn_bridge_hpd_enable,
> + .hpd_disable = ti_sn_bridge_hpd_disable,
> .atomic_pre_enable = ti_sn_bridge_atomic_pre_enable,
> .atomic_enable = ti_sn_bridge_atomic_enable,
> .atomic_disable = ti_sn_bridge_atomic_disable,
> @@ -1223,6 +1282,34 @@ static int ti_sn_bridge_parse_dsi_host(struct ti_sn65dsi86 *pdata)
> return 0;
> }
>
> +static irqreturn_t ti_sn65dsi86_irq_handler(int irq, void *arg)
> +{
> + struct ti_sn65dsi86 *pdata = arg;
> + int ret;
> + unsigned int hpd;
> +
> + ret = regmap_read(pdata->regmap, SN_IRQ_HPD_STATUS_REG, &hpd);
> + if (ret || !hpd)
> + return IRQ_NONE;
> +
> + if (hpd & IRQ_HPD_INSERTION_STATUS)
> + drm_bridge_hpd_notify(&pdata->bridge, connector_status_connected);
> +
> + if (hpd & IRQ_HPD_REMOVAL_STATUS)
> + drm_bridge_hpd_notify(&pdata->bridge, connector_status_disconnected);
> +
> + /* When replugged, ensure we trigger a detect to update the display */
> + if (hpd & IRQ_HPD_REPLUG_STATUS)
> + drm_bridge_hpd_notify(&pdata->bridge, connector_status_disconnected);
> +
> + /* reset the status registers */
> + regmap_write(pdata->regmap, SN_IRQ_HPD_STATUS_REG,
> + IRQ_HPD_STATUS | IRQ_HPD_INSERTION_STATUS |
> + IRQ_HPD_REMOVAL_STATUS | IRQ_HPD_REPLUG_STATUS);
> +
> + return IRQ_HANDLED;
> +}
> +
> static int ti_sn_bridge_probe(struct auxiliary_device *adev,
> const struct auxiliary_device_id *id)
> {
> @@ -1236,6 +1323,14 @@ static int ti_sn_bridge_probe(struct auxiliary_device *adev,
> return PTR_ERR(pdata->next_bridge);
> }
>
> + pdata->no_hpd = of_property_read_bool(np, "no-hpd");
> + if (pdata->next_bridge->type != DRM_MODE_CONNECTOR_DisplayPort &&
> + !pdata->no_hpd) {
> + dev_warn(pdata->dev,
> + "HPD support only implemented for full DP connectors\n");
> + pdata->no_hpd = true;
> + }
> +
> ti_sn_bridge_parse_lanes(pdata, np);
>
> ret = ti_sn_bridge_parse_dsi_host(pdata);
> @@ -1247,9 +1342,29 @@ static int ti_sn_bridge_probe(struct auxiliary_device *adev,
> pdata->bridge.type = pdata->next_bridge->type == DRM_MODE_CONNECTOR_DisplayPort
> ? DRM_MODE_CONNECTOR_DisplayPort : DRM_MODE_CONNECTOR_eDP;
>
> - if (pdata->bridge.type == DRM_MODE_CONNECTOR_DisplayPort)
> + if (pdata->bridge.type == DRM_MODE_CONNECTOR_DisplayPort) {
> pdata->bridge.ops = DRM_BRIDGE_OP_EDID;
>
> + if (!pdata->no_hpd)
> + pdata->bridge.ops |= DRM_BRIDGE_OP_DETECT;
> + }
> +
> + if (!pdata->no_hpd && pdata->irq > 0) {
> + dev_err(pdata->dev, "registering IRQ %d\n", pdata->irq);
Appologies, my debug print has slipped through. This should be removed.
--
Kieran
> +
> + ret = devm_request_threaded_irq(pdata->dev, pdata->irq, NULL,
> + ti_sn65dsi86_irq_handler,
> + IRQF_ONESHOT, "sn65dsi86-irq",
> + pdata);
> + if (ret)
> + return dev_err_probe(pdata->dev, ret,
> + "Failed to register DP interrupt\n");
> +
> + /* Enable IRQ based HPD */
> + regmap_write(pdata->regmap, SN_IRQ_EN_REG, IRQ_EN);
> + pdata->bridge.ops |= DRM_BRIDGE_OP_HPD;
> + }
> +
> drm_bridge_add(&pdata->bridge);
>
> ret = ti_sn_attach_host(pdata);
> @@ -1831,6 +1946,7 @@ static int ti_sn65dsi86_probe(struct i2c_client *client,
> return -ENOMEM;
> dev_set_drvdata(dev, pdata);
> pdata->dev = dev;
> + pdata->irq = client->irq;
>
> mutex_init(&pdata->comms_mutex);
>
> --
> 2.32.0
>
^ permalink raw reply [flat|nested] 16+ messages in thread* Re: [PATCH v3 3/3] drm/bridge: ti-sn65dsi86: Support hotplug detection
2022-03-10 15:22 ` [PATCH v3 3/3] drm/bridge: ti-sn65dsi86: Support hotplug detection Kieran Bingham
2022-03-10 15:26 ` Kieran Bingham
@ 2022-03-10 16:42 ` Laurent Pinchart
2022-03-10 17:39 ` Kieran Bingham
2022-03-10 23:10 ` Doug Anderson
2 siblings, 1 reply; 16+ messages in thread
From: Laurent Pinchart @ 2022-03-10 16:42 UTC (permalink / raw)
To: Kieran Bingham
Cc: dri-devel, linux-renesas-soc, Sam Ravnborg, Douglas Anderson,
linux-kernel, Andrzej Hajda, Neil Armstrong, Robert Foss,
Jonas Karlman, Jernej Skrabec, David Airlie, Daniel Vetter
Hi Kieran,
Thank you for the patch.
On Thu, Mar 10, 2022 at 03:22:27PM +0000, Kieran Bingham wrote:
> When the SN65DSI86 is used in DisplayPort mode, its output is likely
> routed to a DisplayPort connector, which can benefit from hotplug
> detection. Support it in such cases, with polling mode only for now.
Don't we support IRQ mode too now ?
> The implementation is limited to the bridge operations, as the connector
> operations are legacy and new users should use
> DRM_BRIDGE_ATTACH_NO_CONNECTOR.
>
> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
> ---
> Changes since v1:
>
> - Document the no_hpd field
> - Rely on the SN_HPD_DISABLE_REG default value in the HPD case
> - Add a TODO comment regarding IRQ support
> [Kieran]
> - Fix spelling s/assrted/asserted/
> - Only enable HPD on DisplayPort connector.
> - Support IRQ based hotplug detect
>
> Changes since v2: [Kieran]
> - Use unsigned int for values read by regmap
> - Update HPD support warning message
> - Only enable OP_HPD if IRQ support enabled.
> - Only register IRQ handler during ti_sn_bridge_probe()
> - Store IRQ in the struct ti_sn65dsi86
> - Register IRQ only when !no-hpd
> - Refactor DRM_BRIDGE_OP_DETECT and DRM_BRIDGE_OP_HPD handling
>
> drivers/gpu/drm/bridge/ti-sn65dsi86.c | 142 +++++++++++++++++++++++---
> 1 file changed, 129 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> index d581c820e5d8..328a48f09f97 100644
> --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> @@ -70,6 +70,7 @@
> #define BPP_18_RGB BIT(0)
> #define SN_HPD_DISABLE_REG 0x5C
> #define HPD_DISABLE BIT(0)
> +#define HPD_DEBOUNCED_STATE BIT(4)
> #define SN_GPIO_IO_REG 0x5E
> #define SN_GPIO_INPUT_SHIFT 4
> #define SN_GPIO_OUTPUT_SHIFT 0
> @@ -106,10 +107,24 @@
> #define SN_PWM_EN_INV_REG 0xA5
> #define SN_PWM_INV_MASK BIT(0)
> #define SN_PWM_EN_MASK BIT(1)
> +#define SN_IRQ_EN_REG 0xE0
> +#define IRQ_EN BIT(0)
> +#define SN_IRQ_HPD_REG 0xE6
> +#define IRQ_HPD_EN BIT(0)
> +#define IRQ_HPD_INSERTION_EN BIT(1)
> +#define IRQ_HPD_REMOVAL_EN BIT(2)
> +#define IRQ_HPD_REPLUG_EN BIT(3)
> +#define IRQ_HPD_PLL_UNLOCK_EN BIT(5)
> #define SN_AUX_CMD_STATUS_REG 0xF4
> #define AUX_IRQ_STATUS_AUX_RPLY_TOUT BIT(3)
> #define AUX_IRQ_STATUS_AUX_SHORT BIT(5)
> #define AUX_IRQ_STATUS_NAT_I2C_FAIL BIT(6)
> +#define SN_IRQ_HPD_STATUS_REG 0xF5
> +#define IRQ_HPD_STATUS BIT(0)
> +#define IRQ_HPD_INSERTION_STATUS BIT(1)
> +#define IRQ_HPD_REMOVAL_STATUS BIT(2)
> +#define IRQ_HPD_REPLUG_STATUS BIT(3)
> +#define IRQ_PLL_UNLOCK BIT(5)
>
> #define MIN_DSI_CLK_FREQ_MHZ 40
>
> @@ -168,6 +183,12 @@
> * @pwm_enabled: Used to track if the PWM signal is currently enabled.
> * @pwm_pin_busy: Track if GPIO4 is currently requested for GPIO or PWM.
> * @pwm_refclk_freq: Cache for the reference clock input to the PWM.
> + *
> + * @no_hpd: Disable hot-plug detection as instructed by device tree (used
> + * for instance for eDP panels whose HPD signal won't be asserted
> + * until the panel is turned on, and is thus not usable for
> + * downstream device detection).
> + * @irq: IRQ number for the device.
> */
> struct ti_sn65dsi86 {
> struct auxiliary_device bridge_aux;
> @@ -202,6 +223,9 @@ struct ti_sn65dsi86 {
> atomic_t pwm_pin_busy;
> #endif
> unsigned int pwm_refclk_freq;
> +
> + bool no_hpd;
> + int irq;
> };
>
> static const struct regmap_range ti_sn65dsi86_volatile_ranges[] = {
> @@ -316,23 +340,25 @@ static void ti_sn65dsi86_enable_comms(struct ti_sn65dsi86 *pdata)
> ti_sn_bridge_set_refclk_freq(pdata);
>
> /*
> - * HPD on this bridge chip is a bit useless. This is an eDP bridge
> - * so the HPD is an internal signal that's only there to signal that
> - * the panel is done powering up. ...but the bridge chip debounces
> - * this signal by between 100 ms and 400 ms (depending on process,
> - * voltage, and temperate--I measured it at about 200 ms). One
> + * As this is an eDP bridge, the output will be connected to a fixed
> + * panel in most systems. HPD is in that case only an internal signal
> + * to signal that the panel is done powering up. The bridge chip
> + * debounces this signal by between 100 ms and 400 ms (depending on
> + * process, voltage, and temperate--I measured it at about 200 ms). One
> * particular panel asserted HPD 84 ms after it was powered on meaning
> * that we saw HPD 284 ms after power on. ...but the same panel said
> * that instead of looking at HPD you could just hardcode a delay of
> - * 200 ms. We'll assume that the panel driver will have the hardcoded
> - * delay in its prepare and always disable HPD.
> + * 200 ms. HPD is thus a bit useless. For this type of use cases, we'll
> + * assume that the panel driver will have the hardcoded delay in its
> + * prepare and always disable HPD.
> *
> - * If HPD somehow makes sense on some future panel we'll have to
> - * change this to be conditional on someone specifying that HPD should
> - * be used.
> + * However, on some systems, the output is connected to a DisplayPort
> + * connector. HPD is needed in such cases. To accommodate both use
> + * cases, enable HPD only when requested.
> */
> - regmap_update_bits(pdata->regmap, SN_HPD_DISABLE_REG, HPD_DISABLE,
> - HPD_DISABLE);
> + if (pdata->no_hpd)
> + regmap_update_bits(pdata->regmap, SN_HPD_DISABLE_REG,
> + HPD_DISABLE, HPD_DISABLE);
>
> pdata->comms_enabled = true;
>
> @@ -1135,6 +1161,36 @@ static void ti_sn_bridge_atomic_post_disable(struct drm_bridge *bridge,
> pm_runtime_put_sync(pdata->dev);
> }
>
> +static enum drm_connector_status ti_sn_bridge_detect(struct drm_bridge *bridge)
> +{
> + struct ti_sn65dsi86 *pdata = bridge_to_ti_sn65dsi86(bridge);
> + int val;
> +
> + regmap_read(pdata->regmap, SN_HPD_DISABLE_REG, &val);
> +
> + return val & HPD_DEBOUNCED_STATE ? connector_status_connected
> + : connector_status_disconnected;
> +}
> +
> +static void ti_sn_bridge_hpd_enable(struct drm_bridge *bridge)
> +{
> + struct ti_sn65dsi86 *pdata = bridge_to_ti_sn65dsi86(bridge);
> +
> + /* The device must remain active for HPD to function */
> + pm_runtime_get_sync(pdata->dev);
> + regmap_write(pdata->regmap, SN_IRQ_HPD_REG,
> + IRQ_HPD_EN | IRQ_HPD_INSERTION_EN |
> + IRQ_HPD_REMOVAL_EN | IRQ_HPD_REPLUG_EN);
> +}
> +
> +static void ti_sn_bridge_hpd_disable(struct drm_bridge *bridge)
> +{
> + struct ti_sn65dsi86 *pdata = bridge_to_ti_sn65dsi86(bridge);
> +
> + regmap_write(pdata->regmap, SN_IRQ_HPD_REG, 0);
> + pm_runtime_put_autosuspend(pdata->dev);
> +}
> +
> static struct edid *ti_sn_bridge_get_edid(struct drm_bridge *bridge,
> struct drm_connector *connector)
> {
> @@ -1153,6 +1209,9 @@ static const struct drm_bridge_funcs ti_sn_bridge_funcs = {
> .detach = ti_sn_bridge_detach,
> .mode_valid = ti_sn_bridge_mode_valid,
> .get_edid = ti_sn_bridge_get_edid,
> + .detect = ti_sn_bridge_detect,
> + .hpd_enable = ti_sn_bridge_hpd_enable,
> + .hpd_disable = ti_sn_bridge_hpd_disable,
> .atomic_pre_enable = ti_sn_bridge_atomic_pre_enable,
> .atomic_enable = ti_sn_bridge_atomic_enable,
> .atomic_disable = ti_sn_bridge_atomic_disable,
> @@ -1223,6 +1282,34 @@ static int ti_sn_bridge_parse_dsi_host(struct ti_sn65dsi86 *pdata)
> return 0;
> }
>
> +static irqreturn_t ti_sn65dsi86_irq_handler(int irq, void *arg)
> +{
> + struct ti_sn65dsi86 *pdata = arg;
> + int ret;
> + unsigned int hpd;
> +
> + ret = regmap_read(pdata->regmap, SN_IRQ_HPD_STATUS_REG, &hpd);
> + if (ret || !hpd)
> + return IRQ_NONE;
> +
> + if (hpd & IRQ_HPD_INSERTION_STATUS)
> + drm_bridge_hpd_notify(&pdata->bridge, connector_status_connected);
> +
> + if (hpd & IRQ_HPD_REMOVAL_STATUS)
> + drm_bridge_hpd_notify(&pdata->bridge, connector_status_disconnected);
> +
> + /* When replugged, ensure we trigger a detect to update the display */
> + if (hpd & IRQ_HPD_REPLUG_STATUS)
> + drm_bridge_hpd_notify(&pdata->bridge, connector_status_disconnected);
> +
> + /* reset the status registers */
s/registers/register/
> + regmap_write(pdata->regmap, SN_IRQ_HPD_STATUS_REG,
> + IRQ_HPD_STATUS | IRQ_HPD_INSERTION_STATUS |
> + IRQ_HPD_REMOVAL_STATUS | IRQ_HPD_REPLUG_STATUS);
> +
> + return IRQ_HANDLED;
> +}
> +
> static int ti_sn_bridge_probe(struct auxiliary_device *adev,
> const struct auxiliary_device_id *id)
> {
> @@ -1236,6 +1323,14 @@ static int ti_sn_bridge_probe(struct auxiliary_device *adev,
> return PTR_ERR(pdata->next_bridge);
> }
>
> + pdata->no_hpd = of_property_read_bool(np, "no-hpd");
> + if (pdata->next_bridge->type != DRM_MODE_CONNECTOR_DisplayPort &&
> + !pdata->no_hpd) {
> + dev_warn(pdata->dev,
> + "HPD support only implemented for full DP connectors\n");
> + pdata->no_hpd = true;
> + }
> +
> ti_sn_bridge_parse_lanes(pdata, np);
>
> ret = ti_sn_bridge_parse_dsi_host(pdata);
> @@ -1247,9 +1342,29 @@ static int ti_sn_bridge_probe(struct auxiliary_device *adev,
> pdata->bridge.type = pdata->next_bridge->type == DRM_MODE_CONNECTOR_DisplayPort
> ? DRM_MODE_CONNECTOR_DisplayPort : DRM_MODE_CONNECTOR_eDP;
>
> - if (pdata->bridge.type == DRM_MODE_CONNECTOR_DisplayPort)
> + if (pdata->bridge.type == DRM_MODE_CONNECTOR_DisplayPort) {
> pdata->bridge.ops = DRM_BRIDGE_OP_EDID;
>
> + if (!pdata->no_hpd)
> + pdata->bridge.ops |= DRM_BRIDGE_OP_DETECT;
> + }
> +
> + if (!pdata->no_hpd && pdata->irq > 0) {
> + dev_err(pdata->dev, "registering IRQ %d\n", pdata->irq);
As you've noted, this should be removed.
> +
> + ret = devm_request_threaded_irq(pdata->dev, pdata->irq, NULL,
> + ti_sn65dsi86_irq_handler,
> + IRQF_ONESHOT, "sn65dsi86-irq",
> + pdata);
> + if (ret)
> + return dev_err_probe(pdata->dev, ret,
> + "Failed to register DP interrupt\n");
> +
> + /* Enable IRQ based HPD */
> + regmap_write(pdata->regmap, SN_IRQ_EN_REG, IRQ_EN);
Do we have a guarantee that the device isn't PM-suspended here ? Should
this be done in the PM resume handler ?
> + pdata->bridge.ops |= DRM_BRIDGE_OP_HPD;
> + }
> +
> drm_bridge_add(&pdata->bridge);
>
> ret = ti_sn_attach_host(pdata);
> @@ -1831,6 +1946,7 @@ static int ti_sn65dsi86_probe(struct i2c_client *client,
> return -ENOMEM;
> dev_set_drvdata(dev, pdata);
> pdata->dev = dev;
> + pdata->irq = client->irq;
>
> mutex_init(&pdata->comms_mutex);
>
--
Regards,
Laurent Pinchart
^ permalink raw reply [flat|nested] 16+ messages in thread* Re: [PATCH v3 3/3] drm/bridge: ti-sn65dsi86: Support hotplug detection
2022-03-10 16:42 ` Laurent Pinchart
@ 2022-03-10 17:39 ` Kieran Bingham
0 siblings, 0 replies; 16+ messages in thread
From: Kieran Bingham @ 2022-03-10 17:39 UTC (permalink / raw)
To: Laurent Pinchart
Cc: dri-devel, linux-renesas-soc, Sam Ravnborg, Douglas Anderson,
linux-kernel, Andrzej Hajda, Neil Armstrong, Robert Foss,
Jonas Karlman, Jernej Skrabec, David Airlie, Daniel Vetter
Hi Laurent
Quoting Laurent Pinchart (2022-03-10 16:42:48)
> Hi Kieran,
>
> Thank you for the patch.
>
> On Thu, Mar 10, 2022 at 03:22:27PM +0000, Kieran Bingham wrote:
> > When the SN65DSI86 is used in DisplayPort mode, its output is likely
> > routed to a DisplayPort connector, which can benefit from hotplug
> > detection. Support it in such cases, with polling mode only for now.
>
> Don't we support IRQ mode too now ?
Ah yes, I missed this for an update.
> > The implementation is limited to the bridge operations, as the connector
> > operations are legacy and new users should use
> > DRM_BRIDGE_ATTACH_NO_CONNECTOR.
> >
> > Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> > Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
> > ---
> > Changes since v1:
> >
> > - Document the no_hpd field
> > - Rely on the SN_HPD_DISABLE_REG default value in the HPD case
> > - Add a TODO comment regarding IRQ support
> > [Kieran]
> > - Fix spelling s/assrted/asserted/
> > - Only enable HPD on DisplayPort connector.
> > - Support IRQ based hotplug detect
> >
> > Changes since v2: [Kieran]
> > - Use unsigned int for values read by regmap
> > - Update HPD support warning message
> > - Only enable OP_HPD if IRQ support enabled.
> > - Only register IRQ handler during ti_sn_bridge_probe()
> > - Store IRQ in the struct ti_sn65dsi86
> > - Register IRQ only when !no-hpd
> > - Refactor DRM_BRIDGE_OP_DETECT and DRM_BRIDGE_OP_HPD handling
> >
> > drivers/gpu/drm/bridge/ti-sn65dsi86.c | 142 +++++++++++++++++++++++---
> > 1 file changed, 129 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> > index d581c820e5d8..328a48f09f97 100644
> > --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> > +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> > @@ -70,6 +70,7 @@
> > #define BPP_18_RGB BIT(0)
> > #define SN_HPD_DISABLE_REG 0x5C
> > #define HPD_DISABLE BIT(0)
> > +#define HPD_DEBOUNCED_STATE BIT(4)
> > #define SN_GPIO_IO_REG 0x5E
> > #define SN_GPIO_INPUT_SHIFT 4
> > #define SN_GPIO_OUTPUT_SHIFT 0
> > @@ -106,10 +107,24 @@
> > #define SN_PWM_EN_INV_REG 0xA5
> > #define SN_PWM_INV_MASK BIT(0)
> > #define SN_PWM_EN_MASK BIT(1)
> > +#define SN_IRQ_EN_REG 0xE0
> > +#define IRQ_EN BIT(0)
> > +#define SN_IRQ_HPD_REG 0xE6
> > +#define IRQ_HPD_EN BIT(0)
> > +#define IRQ_HPD_INSERTION_EN BIT(1)
> > +#define IRQ_HPD_REMOVAL_EN BIT(2)
> > +#define IRQ_HPD_REPLUG_EN BIT(3)
> > +#define IRQ_HPD_PLL_UNLOCK_EN BIT(5)
> > #define SN_AUX_CMD_STATUS_REG 0xF4
> > #define AUX_IRQ_STATUS_AUX_RPLY_TOUT BIT(3)
> > #define AUX_IRQ_STATUS_AUX_SHORT BIT(5)
> > #define AUX_IRQ_STATUS_NAT_I2C_FAIL BIT(6)
> > +#define SN_IRQ_HPD_STATUS_REG 0xF5
> > +#define IRQ_HPD_STATUS BIT(0)
> > +#define IRQ_HPD_INSERTION_STATUS BIT(1)
> > +#define IRQ_HPD_REMOVAL_STATUS BIT(2)
> > +#define IRQ_HPD_REPLUG_STATUS BIT(3)
> > +#define IRQ_PLL_UNLOCK BIT(5)
> >
> > #define MIN_DSI_CLK_FREQ_MHZ 40
> >
> > @@ -168,6 +183,12 @@
> > * @pwm_enabled: Used to track if the PWM signal is currently enabled.
> > * @pwm_pin_busy: Track if GPIO4 is currently requested for GPIO or PWM.
> > * @pwm_refclk_freq: Cache for the reference clock input to the PWM.
> > + *
> > + * @no_hpd: Disable hot-plug detection as instructed by device tree (used
> > + * for instance for eDP panels whose HPD signal won't be asserted
> > + * until the panel is turned on, and is thus not usable for
> > + * downstream device detection).
> > + * @irq: IRQ number for the device.
> > */
> > struct ti_sn65dsi86 {
> > struct auxiliary_device bridge_aux;
> > @@ -202,6 +223,9 @@ struct ti_sn65dsi86 {
> > atomic_t pwm_pin_busy;
> > #endif
> > unsigned int pwm_refclk_freq;
> > +
> > + bool no_hpd;
> > + int irq;
> > };
> >
> > static const struct regmap_range ti_sn65dsi86_volatile_ranges[] = {
> > @@ -316,23 +340,25 @@ static void ti_sn65dsi86_enable_comms(struct ti_sn65dsi86 *pdata)
> > ti_sn_bridge_set_refclk_freq(pdata);
> >
> > /*
> > - * HPD on this bridge chip is a bit useless. This is an eDP bridge
> > - * so the HPD is an internal signal that's only there to signal that
> > - * the panel is done powering up. ...but the bridge chip debounces
> > - * this signal by between 100 ms and 400 ms (depending on process,
> > - * voltage, and temperate--I measured it at about 200 ms). One
> > + * As this is an eDP bridge, the output will be connected to a fixed
> > + * panel in most systems. HPD is in that case only an internal signal
> > + * to signal that the panel is done powering up. The bridge chip
> > + * debounces this signal by between 100 ms and 400 ms (depending on
> > + * process, voltage, and temperate--I measured it at about 200 ms). One
> > * particular panel asserted HPD 84 ms after it was powered on meaning
> > * that we saw HPD 284 ms after power on. ...but the same panel said
> > * that instead of looking at HPD you could just hardcode a delay of
> > - * 200 ms. We'll assume that the panel driver will have the hardcoded
> > - * delay in its prepare and always disable HPD.
> > + * 200 ms. HPD is thus a bit useless. For this type of use cases, we'll
> > + * assume that the panel driver will have the hardcoded delay in its
> > + * prepare and always disable HPD.
> > *
> > - * If HPD somehow makes sense on some future panel we'll have to
> > - * change this to be conditional on someone specifying that HPD should
> > - * be used.
> > + * However, on some systems, the output is connected to a DisplayPort
> > + * connector. HPD is needed in such cases. To accommodate both use
> > + * cases, enable HPD only when requested.
> > */
> > - regmap_update_bits(pdata->regmap, SN_HPD_DISABLE_REG, HPD_DISABLE,
> > - HPD_DISABLE);
> > + if (pdata->no_hpd)
> > + regmap_update_bits(pdata->regmap, SN_HPD_DISABLE_REG,
> > + HPD_DISABLE, HPD_DISABLE);
> >
> > pdata->comms_enabled = true;
> >
> > @@ -1135,6 +1161,36 @@ static void ti_sn_bridge_atomic_post_disable(struct drm_bridge *bridge,
> > pm_runtime_put_sync(pdata->dev);
> > }
> >
> > +static enum drm_connector_status ti_sn_bridge_detect(struct drm_bridge *bridge)
> > +{
> > + struct ti_sn65dsi86 *pdata = bridge_to_ti_sn65dsi86(bridge);
> > + int val;
> > +
> > + regmap_read(pdata->regmap, SN_HPD_DISABLE_REG, &val);
> > +
> > + return val & HPD_DEBOUNCED_STATE ? connector_status_connected
> > + : connector_status_disconnected;
> > +}
> > +
> > +static void ti_sn_bridge_hpd_enable(struct drm_bridge *bridge)
> > +{
> > + struct ti_sn65dsi86 *pdata = bridge_to_ti_sn65dsi86(bridge);
> > +
> > + /* The device must remain active for HPD to function */
> > + pm_runtime_get_sync(pdata->dev);
> > + regmap_write(pdata->regmap, SN_IRQ_HPD_REG,
> > + IRQ_HPD_EN | IRQ_HPD_INSERTION_EN |
> > + IRQ_HPD_REMOVAL_EN | IRQ_HPD_REPLUG_EN);
> > +}
> > +
> > +static void ti_sn_bridge_hpd_disable(struct drm_bridge *bridge)
> > +{
> > + struct ti_sn65dsi86 *pdata = bridge_to_ti_sn65dsi86(bridge);
> > +
> > + regmap_write(pdata->regmap, SN_IRQ_HPD_REG, 0);
> > + pm_runtime_put_autosuspend(pdata->dev);
> > +}
> > +
> > static struct edid *ti_sn_bridge_get_edid(struct drm_bridge *bridge,
> > struct drm_connector *connector)
> > {
> > @@ -1153,6 +1209,9 @@ static const struct drm_bridge_funcs ti_sn_bridge_funcs = {
> > .detach = ti_sn_bridge_detach,
> > .mode_valid = ti_sn_bridge_mode_valid,
> > .get_edid = ti_sn_bridge_get_edid,
> > + .detect = ti_sn_bridge_detect,
> > + .hpd_enable = ti_sn_bridge_hpd_enable,
> > + .hpd_disable = ti_sn_bridge_hpd_disable,
> > .atomic_pre_enable = ti_sn_bridge_atomic_pre_enable,
> > .atomic_enable = ti_sn_bridge_atomic_enable,
> > .atomic_disable = ti_sn_bridge_atomic_disable,
> > @@ -1223,6 +1282,34 @@ static int ti_sn_bridge_parse_dsi_host(struct ti_sn65dsi86 *pdata)
> > return 0;
> > }
> >
> > +static irqreturn_t ti_sn65dsi86_irq_handler(int irq, void *arg)
> > +{
> > + struct ti_sn65dsi86 *pdata = arg;
> > + int ret;
> > + unsigned int hpd;
> > +
> > + ret = regmap_read(pdata->regmap, SN_IRQ_HPD_STATUS_REG, &hpd);
> > + if (ret || !hpd)
> > + return IRQ_NONE;
> > +
> > + if (hpd & IRQ_HPD_INSERTION_STATUS)
> > + drm_bridge_hpd_notify(&pdata->bridge, connector_status_connected);
> > +
> > + if (hpd & IRQ_HPD_REMOVAL_STATUS)
> > + drm_bridge_hpd_notify(&pdata->bridge, connector_status_disconnected);
> > +
> > + /* When replugged, ensure we trigger a detect to update the display */
> > + if (hpd & IRQ_HPD_REPLUG_STATUS)
> > + drm_bridge_hpd_notify(&pdata->bridge, connector_status_disconnected);
> > +
> > + /* reset the status registers */
>
> s/registers/register/
Ack.
>
> > + regmap_write(pdata->regmap, SN_IRQ_HPD_STATUS_REG,
> > + IRQ_HPD_STATUS | IRQ_HPD_INSERTION_STATUS |
> > + IRQ_HPD_REMOVAL_STATUS | IRQ_HPD_REPLUG_STATUS);
> > +
> > + return IRQ_HANDLED;
> > +}
> > +
> > static int ti_sn_bridge_probe(struct auxiliary_device *adev,
> > const struct auxiliary_device_id *id)
> > {
> > @@ -1236,6 +1323,14 @@ static int ti_sn_bridge_probe(struct auxiliary_device *adev,
> > return PTR_ERR(pdata->next_bridge);
> > }
> >
> > + pdata->no_hpd = of_property_read_bool(np, "no-hpd");
> > + if (pdata->next_bridge->type != DRM_MODE_CONNECTOR_DisplayPort &&
> > + !pdata->no_hpd) {
> > + dev_warn(pdata->dev,
> > + "HPD support only implemented for full DP connectors\n");
> > + pdata->no_hpd = true;
> > + }
> > +
> > ti_sn_bridge_parse_lanes(pdata, np);
> >
> > ret = ti_sn_bridge_parse_dsi_host(pdata);
> > @@ -1247,9 +1342,29 @@ static int ti_sn_bridge_probe(struct auxiliary_device *adev,
> > pdata->bridge.type = pdata->next_bridge->type == DRM_MODE_CONNECTOR_DisplayPort
> > ? DRM_MODE_CONNECTOR_DisplayPort : DRM_MODE_CONNECTOR_eDP;
> >
> > - if (pdata->bridge.type == DRM_MODE_CONNECTOR_DisplayPort)
> > + if (pdata->bridge.type == DRM_MODE_CONNECTOR_DisplayPort) {
> > pdata->bridge.ops = DRM_BRIDGE_OP_EDID;
> >
> > + if (!pdata->no_hpd)
> > + pdata->bridge.ops |= DRM_BRIDGE_OP_DETECT;
> > + }
> > +
> > + if (!pdata->no_hpd && pdata->irq > 0) {
> > + dev_err(pdata->dev, "registering IRQ %d\n", pdata->irq);
>
> As you've noted, this should be removed.
Already gone in my tree.
>
> > +
> > + ret = devm_request_threaded_irq(pdata->dev, pdata->irq, NULL,
> > + ti_sn65dsi86_irq_handler,
> > + IRQF_ONESHOT, "sn65dsi86-irq",
> > + pdata);
> > + if (ret)
> > + return dev_err_probe(pdata->dev, ret,
> > + "Failed to register DP interrupt\n");
> > +
> > + /* Enable IRQ based HPD */
> > + regmap_write(pdata->regmap, SN_IRQ_EN_REG, IRQ_EN);
>
> Do we have a guarantee that the device isn't PM-suspended here ? Should
> this be done in the PM resume handler ?
This is tricky I fear. The ti_sn_bridge_probe() is called after the main
ti_sn65dsi86_probe(), which is where the pm resume handler would get
called first.
I moved the handler registration here, because we can't handle the IRQ
until we have the bridge set up, but if we were to enable interrupts in
the pm resume handler, it would get enabled during ti_sn65dsi86_probe()
before the handler is registered.
Now at that point nothing should fire an interrupt, but still - enabling
interrupts before the handler is registered doesn't sound good to me.
--
Kieran
>
> > + pdata->bridge.ops |= DRM_BRIDGE_OP_HPD;
> > + }
> > +
> > drm_bridge_add(&pdata->bridge);
> >
> > ret = ti_sn_attach_host(pdata);
> > @@ -1831,6 +1946,7 @@ static int ti_sn65dsi86_probe(struct i2c_client *client,
> > return -ENOMEM;
> > dev_set_drvdata(dev, pdata);
> > pdata->dev = dev;
> > + pdata->irq = client->irq;
> >
> > mutex_init(&pdata->comms_mutex);
> >
>
> --
> Regards,
>
> Laurent Pinchart
^ permalink raw reply [flat|nested] 16+ messages in thread
* Re: [PATCH v3 3/3] drm/bridge: ti-sn65dsi86: Support hotplug detection
2022-03-10 15:22 ` [PATCH v3 3/3] drm/bridge: ti-sn65dsi86: Support hotplug detection Kieran Bingham
2022-03-10 15:26 ` Kieran Bingham
2022-03-10 16:42 ` Laurent Pinchart
@ 2022-03-10 23:10 ` Doug Anderson
2022-03-11 5:47 ` Kieran Bingham
2 siblings, 1 reply; 16+ messages in thread
From: Doug Anderson @ 2022-03-10 23:10 UTC (permalink / raw)
To: Kieran Bingham
Cc: dri-devel, Linux-Renesas, Sam Ravnborg, LKML, Andrzej Hajda,
Neil Armstrong, Robert Foss, Laurent Pinchart, Jonas Karlman,
Jernej Skrabec, David Airlie, Daniel Vetter, Laurent Pinchart
Hi,
On Thu, Mar 10, 2022 at 7:22 AM Kieran Bingham
<kieran.bingham+renesas@ideasonboard.com> wrote:
>
> @@ -1135,6 +1161,36 @@ static void ti_sn_bridge_atomic_post_disable(struct drm_bridge *bridge,
> pm_runtime_put_sync(pdata->dev);
> }
>
> +static enum drm_connector_status ti_sn_bridge_detect(struct drm_bridge *bridge)
> +{
> + struct ti_sn65dsi86 *pdata = bridge_to_ti_sn65dsi86(bridge);
> + int val;
> +
> + regmap_read(pdata->regmap, SN_HPD_DISABLE_REG, &val);
Don't you need a pm_runtime_get_sync() before this and a
put_autosuspend() after? The "detect" will be used in the yes-HPD but
no-IRQ case, right? In that case there's nobody holding the pm_runtime
reference.
Also, a nit that it'd be great if you error checked the regmap_read().
I know this driver isn't very good about it, but it's probably
something to get better. i2c transactions can fail. I guess another
alternative would be to init "val" to 0...
> + return val & HPD_DEBOUNCED_STATE ? connector_status_connected
> + : connector_status_disconnected;
> +}
> +
> +static void ti_sn_bridge_hpd_enable(struct drm_bridge *bridge)
> +{
> + struct ti_sn65dsi86 *pdata = bridge_to_ti_sn65dsi86(bridge);
> +
> + /* The device must remain active for HPD to function */
> + pm_runtime_get_sync(pdata->dev);
> + regmap_write(pdata->regmap, SN_IRQ_HPD_REG,
> + IRQ_HPD_EN | IRQ_HPD_INSERTION_EN |
> + IRQ_HPD_REMOVAL_EN | IRQ_HPD_REPLUG_EN);
> +}
> +
> +static void ti_sn_bridge_hpd_disable(struct drm_bridge *bridge)
> +{
> + struct ti_sn65dsi86 *pdata = bridge_to_ti_sn65dsi86(bridge);
> +
> + regmap_write(pdata->regmap, SN_IRQ_HPD_REG, 0);
> + pm_runtime_put_autosuspend(pdata->dev);
Before doing the pm_runtime_put_autosuspend() it feels like you should
ensure that the interrupt has finished. Otherwise we could be midway
through processing an interrupt and the pm_runtime reference could go
away, right? Maybe we just disable the irq which I think will wait for
anything outstanding to finish?
> @@ -1223,6 +1282,34 @@ static int ti_sn_bridge_parse_dsi_host(struct ti_sn65dsi86 *pdata)
> return 0;
> }
>
> +static irqreturn_t ti_sn65dsi86_irq_handler(int irq, void *arg)
> +{
> + struct ti_sn65dsi86 *pdata = arg;
> + int ret;
> + unsigned int hpd;
> +
> + ret = regmap_read(pdata->regmap, SN_IRQ_HPD_STATUS_REG, &hpd);
> + if (ret || !hpd)
> + return IRQ_NONE;
> +
> + if (hpd & IRQ_HPD_INSERTION_STATUS)
> + drm_bridge_hpd_notify(&pdata->bridge, connector_status_connected);
> +
> + if (hpd & IRQ_HPD_REMOVAL_STATUS)
> + drm_bridge_hpd_notify(&pdata->bridge, connector_status_disconnected);
> +
> + /* When replugged, ensure we trigger a detect to update the display */
> + if (hpd & IRQ_HPD_REPLUG_STATUS)
> + drm_bridge_hpd_notify(&pdata->bridge, connector_status_disconnected);
How does the ordering work here if _both_ insertion and removal are
asserted? Is that somehow not possible? Should this be "else if" type
statements then, or give a warn if more than one bit is set, or ... ?
> + /* reset the status registers */
> + regmap_write(pdata->regmap, SN_IRQ_HPD_STATUS_REG,
> + IRQ_HPD_STATUS | IRQ_HPD_INSERTION_STATUS |
> + IRQ_HPD_REMOVAL_STATUS | IRQ_HPD_REPLUG_STATUS);
IMO this regmap_write() belongs right after the read and should be
based on what you read--you shouldn't just clear all of them. AKA:
a) Read to see what interrupt are asserted.
b) Ack the interrupts that you saw asserted.
c) Process the interrupts that you saw asserted.
If you process before acking then you can miss interrupts (in other
words if you do "a" then "c" then "b" then you can miss interrupts
that come in after "b" but before "c".
> @@ -1247,9 +1342,29 @@ static int ti_sn_bridge_probe(struct auxiliary_device *adev,
> pdata->bridge.type = pdata->next_bridge->type == DRM_MODE_CONNECTOR_DisplayPort
> ? DRM_MODE_CONNECTOR_DisplayPort : DRM_MODE_CONNECTOR_eDP;
>
> - if (pdata->bridge.type == DRM_MODE_CONNECTOR_DisplayPort)
> + if (pdata->bridge.type == DRM_MODE_CONNECTOR_DisplayPort) {
> pdata->bridge.ops = DRM_BRIDGE_OP_EDID;
>
> + if (!pdata->no_hpd)
> + pdata->bridge.ops |= DRM_BRIDGE_OP_DETECT;
> + }
> +
> + if (!pdata->no_hpd && pdata->irq > 0) {
> + dev_err(pdata->dev, "registering IRQ %d\n", pdata->irq);
> +
> + ret = devm_request_threaded_irq(pdata->dev, pdata->irq, NULL,
> + ti_sn65dsi86_irq_handler,
> + IRQF_ONESHOT, "sn65dsi86-irq",
> + pdata);
> + if (ret)
> + return dev_err_probe(pdata->dev, ret,
> + "Failed to register DP interrupt\n");
> +
> + /* Enable IRQ based HPD */
> + regmap_write(pdata->regmap, SN_IRQ_EN_REG, IRQ_EN);
Why not put the above regmap_write() in the ti_sn_bridge_hpd_enable() call?
-Doug
^ permalink raw reply [flat|nested] 16+ messages in thread* Re: [PATCH v3 3/3] drm/bridge: ti-sn65dsi86: Support hotplug detection
2022-03-10 23:10 ` Doug Anderson
@ 2022-03-11 5:47 ` Kieran Bingham
2022-03-11 15:24 ` Doug Anderson
0 siblings, 1 reply; 16+ messages in thread
From: Kieran Bingham @ 2022-03-11 5:47 UTC (permalink / raw)
To: Doug Anderson
Cc: dri-devel, Linux-Renesas, Sam Ravnborg, LKML, Andrzej Hajda,
Neil Armstrong, Robert Foss, Laurent Pinchart, Jonas Karlman,
Jernej Skrabec, David Airlie, Daniel Vetter, Laurent Pinchart
Hi Doug,
Quoting Doug Anderson (2022-03-10 23:10:12)
> Hi,
>
> On Thu, Mar 10, 2022 at 7:22 AM Kieran Bingham
> <kieran.bingham+renesas@ideasonboard.com> wrote:
> >
> > @@ -1135,6 +1161,36 @@ static void ti_sn_bridge_atomic_post_disable(struct drm_bridge *bridge,
> > pm_runtime_put_sync(pdata->dev);
> > }
> >
> > +static enum drm_connector_status ti_sn_bridge_detect(struct drm_bridge *bridge)
> > +{
> > + struct ti_sn65dsi86 *pdata = bridge_to_ti_sn65dsi86(bridge);
> > + int val;
> > +
> > + regmap_read(pdata->regmap, SN_HPD_DISABLE_REG, &val);
>
> Don't you need a pm_runtime_get_sync() before this and a
> put_autosuspend() after? The "detect" will be used in the yes-HPD but
> no-IRQ case, right? In that case there's nobody holding the pm_runtime
> reference.
Hrm ... I'll have to dig on this a bit. The polling is done by the DRM
core, so indeed I suspect it could be done outside of a context that
holds the pm runtime reference.
Equally a get and put on the reference doesn't hurt even if it's already
taken, so perhaps it's best to add it, but I'll try to confirm it's
requirement first.
> Also, a nit that it'd be great if you error checked the regmap_read().
> I know this driver isn't very good about it, but it's probably
> something to get better. i2c transactions can fail. I guess another
> alternative would be to init "val" to 0...
It's a good point indeed. If we can't read the device we should return
disconnected.
>
>
> > + return val & HPD_DEBOUNCED_STATE ? connector_status_connected
> > + : connector_status_disconnected;
> > +}
> > +
> > +static void ti_sn_bridge_hpd_enable(struct drm_bridge *bridge)
> > +{
> > + struct ti_sn65dsi86 *pdata = bridge_to_ti_sn65dsi86(bridge);
> > +
> > + /* The device must remain active for HPD to function */
> > + pm_runtime_get_sync(pdata->dev);
> > + regmap_write(pdata->regmap, SN_IRQ_HPD_REG,
> > + IRQ_HPD_EN | IRQ_HPD_INSERTION_EN |
> > + IRQ_HPD_REMOVAL_EN | IRQ_HPD_REPLUG_EN);
> > +}
> > +
> > +static void ti_sn_bridge_hpd_disable(struct drm_bridge *bridge)
> > +{
> > + struct ti_sn65dsi86 *pdata = bridge_to_ti_sn65dsi86(bridge);
> > +
> > + regmap_write(pdata->regmap, SN_IRQ_HPD_REG, 0);
> > + pm_runtime_put_autosuspend(pdata->dev);
>
> Before doing the pm_runtime_put_autosuspend() it feels like you should
> ensure that the interrupt has finished. Otherwise we could be midway
> through processing an interrupt and the pm_runtime reference could go
> away, right? Maybe we just disable the irq which I think will wait for
> anything outstanding to finish?
Should the IRQ handler also call pm_runtime_get/put then?
> > @@ -1223,6 +1282,34 @@ static int ti_sn_bridge_parse_dsi_host(struct ti_sn65dsi86 *pdata)
> > return 0;
> > }
> >
> > +static irqreturn_t ti_sn65dsi86_irq_handler(int irq, void *arg)
> > +{
> > + struct ti_sn65dsi86 *pdata = arg;
> > + int ret;
> > + unsigned int hpd;
> > +
> > + ret = regmap_read(pdata->regmap, SN_IRQ_HPD_STATUS_REG, &hpd);
> > + if (ret || !hpd)
> > + return IRQ_NONE;
> > +
> > + if (hpd & IRQ_HPD_INSERTION_STATUS)
> > + drm_bridge_hpd_notify(&pdata->bridge, connector_status_connected);
> > +
> > + if (hpd & IRQ_HPD_REMOVAL_STATUS)
> > + drm_bridge_hpd_notify(&pdata->bridge, connector_status_disconnected);
> > +
> > + /* When replugged, ensure we trigger a detect to update the display */
> > + if (hpd & IRQ_HPD_REPLUG_STATUS)
> > + drm_bridge_hpd_notify(&pdata->bridge, connector_status_disconnected);
>
> How does the ordering work here if _both_ insertion and removal are
> asserted? Is that somehow not possible? Should this be "else if" type
> statements then, or give a warn if more than one bit is set, or ... ?
As I understand it, that would trigger a REPLUG IRQ. However this is one
part I quite disliked about the drm_bridge_hpd_notify. The values here
are not taken as the hardware state anyway. A call to drm_bridge_hpd_notify will
trigger a call on the detect function so a further read will occur to
determine the current state using the same function as is used with
polling.
The IRQ handler only cuts out the polling as far as I see.
> > + /* reset the status registers */
> > + regmap_write(pdata->regmap, SN_IRQ_HPD_STATUS_REG,
> > + IRQ_HPD_STATUS | IRQ_HPD_INSERTION_STATUS |
> > + IRQ_HPD_REMOVAL_STATUS | IRQ_HPD_REPLUG_STATUS);
>
> IMO this regmap_write() belongs right after the read and should be
> based on what you read--you shouldn't just clear all of them. AKA:
>
> a) Read to see what interrupt are asserted.
> b) Ack the interrupts that you saw asserted.
> c) Process the interrupts that you saw asserted.
>
> If you process before acking then you can miss interrupts (in other
> words if you do "a" then "c" then "b" then you can miss interrupts
> that come in after "b" but before "c".
Agreed, I'll respin.
> > @@ -1247,9 +1342,29 @@ static int ti_sn_bridge_probe(struct auxiliary_device *adev,
> > pdata->bridge.type = pdata->next_bridge->type == DRM_MODE_CONNECTOR_DisplayPort
> > ? DRM_MODE_CONNECTOR_DisplayPort : DRM_MODE_CONNECTOR_eDP;
> >
> > - if (pdata->bridge.type == DRM_MODE_CONNECTOR_DisplayPort)
> > + if (pdata->bridge.type == DRM_MODE_CONNECTOR_DisplayPort) {
> > pdata->bridge.ops = DRM_BRIDGE_OP_EDID;
> >
> > + if (!pdata->no_hpd)
> > + pdata->bridge.ops |= DRM_BRIDGE_OP_DETECT;
> > + }
> > +
> > + if (!pdata->no_hpd && pdata->irq > 0) {
> > + dev_err(pdata->dev, "registering IRQ %d\n", pdata->irq);
> > +
> > + ret = devm_request_threaded_irq(pdata->dev, pdata->irq, NULL,
> > + ti_sn65dsi86_irq_handler,
> > + IRQF_ONESHOT, "sn65dsi86-irq",
> > + pdata);
> > + if (ret)
> > + return dev_err_probe(pdata->dev, ret,
> > + "Failed to register DP interrupt\n");
> > +
> > + /* Enable IRQ based HPD */
> > + regmap_write(pdata->regmap, SN_IRQ_EN_REG, IRQ_EN);
>
> Why not put the above regmap_write() in the ti_sn_bridge_hpd_enable() call?
I assumed the IRQ handler may get used by other non-HPD events. Which is
also why it was originally registered in the main probe(). HPD is just
one feature of the interrupts. Of course it's only used for HPD now
though. I guess I could have solved the bridge dependency by splitting
the IRQ handler to have a dedicated HPD handler function which would
return if the bridge wasn't initialised, but went with the deferred
registration of the handler.
I can move this and then leave it to anyone else implementing further
IRQ features to refactor if needed.
>
> -Doug
^ permalink raw reply [flat|nested] 16+ messages in thread* Re: [PATCH v3 3/3] drm/bridge: ti-sn65dsi86: Support hotplug detection
2022-03-11 5:47 ` Kieran Bingham
@ 2022-03-11 15:24 ` Doug Anderson
0 siblings, 0 replies; 16+ messages in thread
From: Doug Anderson @ 2022-03-11 15:24 UTC (permalink / raw)
To: Kieran Bingham
Cc: dri-devel, Linux-Renesas, Sam Ravnborg, LKML, Andrzej Hajda,
Neil Armstrong, Robert Foss, Laurent Pinchart, Jonas Karlman,
Jernej Skrabec, David Airlie, Daniel Vetter, Laurent Pinchart
Hi,
On Thu, Mar 10, 2022 at 9:47 PM Kieran Bingham
<kieran.bingham+renesas@ideasonboard.com> wrote:
>
> > > +static void ti_sn_bridge_hpd_disable(struct drm_bridge *bridge)
> > > +{
> > > + struct ti_sn65dsi86 *pdata = bridge_to_ti_sn65dsi86(bridge);
> > > +
> > > + regmap_write(pdata->regmap, SN_IRQ_HPD_REG, 0);
> > > + pm_runtime_put_autosuspend(pdata->dev);
> >
> > Before doing the pm_runtime_put_autosuspend() it feels like you should
> > ensure that the interrupt has finished. Otherwise we could be midway
> > through processing an interrupt and the pm_runtime reference could go
> > away, right? Maybe we just disable the irq which I think will wait for
> > anything outstanding to finish?
>
> Should the IRQ handler also call pm_runtime_get/put then?
I thought about that, but I suspect it's cleaner to disable the IRQ
handler (and block waiting for it to finish if it was running). That
will ensure that the core isn't notified about HPD after HPD was
disabled. Once you do that then there's no need to get/put in the irq
handler since we always hold a pm_runtime reference when the IRQ
handler is enabled.
> > > @@ -1247,9 +1342,29 @@ static int ti_sn_bridge_probe(struct auxiliary_device *adev,
> > > pdata->bridge.type = pdata->next_bridge->type == DRM_MODE_CONNECTOR_DisplayPort
> > > ? DRM_MODE_CONNECTOR_DisplayPort : DRM_MODE_CONNECTOR_eDP;
> > >
> > > - if (pdata->bridge.type == DRM_MODE_CONNECTOR_DisplayPort)
> > > + if (pdata->bridge.type == DRM_MODE_CONNECTOR_DisplayPort) {
> > > pdata->bridge.ops = DRM_BRIDGE_OP_EDID;
> > >
> > > + if (!pdata->no_hpd)
> > > + pdata->bridge.ops |= DRM_BRIDGE_OP_DETECT;
> > > + }
> > > +
> > > + if (!pdata->no_hpd && pdata->irq > 0) {
> > > + dev_err(pdata->dev, "registering IRQ %d\n", pdata->irq);
> > > +
> > > + ret = devm_request_threaded_irq(pdata->dev, pdata->irq, NULL,
> > > + ti_sn65dsi86_irq_handler,
> > > + IRQF_ONESHOT, "sn65dsi86-irq",
> > > + pdata);
> > > + if (ret)
> > > + return dev_err_probe(pdata->dev, ret,
> > > + "Failed to register DP interrupt\n");
> > > +
> > > + /* Enable IRQ based HPD */
> > > + regmap_write(pdata->regmap, SN_IRQ_EN_REG, IRQ_EN);
> >
> > Why not put the above regmap_write() in the ti_sn_bridge_hpd_enable() call?
>
> I assumed the IRQ handler may get used by other non-HPD events. Which is
> also why it was originally registered in the main probe(). HPD is just
> one feature of the interrupts. Of course it's only used for HPD now
> though. I guess I could have solved the bridge dependency by splitting
> the IRQ handler to have a dedicated HPD handler function which would
> return if the bridge wasn't initialised, but went with the deferred
> registration of the handler.
>
> I can move this and then leave it to anyone else implementing further
> IRQ features to refactor if needed.
Sounds good. In general the pm_runtime_get reference need to go with
the IRQ enabling, so if someone else finds a non-HPD need then they'll
have to move that too.
^ permalink raw reply [flat|nested] 16+ messages in thread