Re: [PATCH v2 2/2] drm: bridge: Move HPD handling to PHY operations

From: Laurent Pinchart
Date: Thu Mar 02 2017 - 11:19:51 EST


Hi Neil,

Thank you for the patch.

On Thursday 02 Mar 2017 16:29:32 Neil Armstrong wrote:
> The HDMI TX controller support HPD and RXSENSE signaling from the PHY
> via it's STAT0 PHY interface, but some vendor PHYs can manage these
> signals independently from the controller, thus these STAT0 handling
> should be moved to PHY specific operations and become optional.
>
> The existing STAT0 HPD and RXSENSE handling code is refactored into
> a supplementaty set of default PHY operations that are used automatically
> when the platform glue doesn't provide its own operations.
>
> Signed-off-by: Neil Armstrong <narmstrong@xxxxxxxxxxxx>
> ---
> drivers/gpu/drm/bridge/dw-hdmi.c | 134 +++++++++++++++++++++++++-----------
> include/drm/bridge/dw_hdmi.h | 8 +++
> 2 files changed, 104 insertions(+), 38 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/dw-hdmi.c
> b/drivers/gpu/drm/bridge/dw-hdmi.c index 653ecd7..58dcf7d 100644
> --- a/drivers/gpu/drm/bridge/dw-hdmi.c
> +++ b/drivers/gpu/drm/bridge/dw-hdmi.c
> @@ -1098,10 +1098,50 @@ static enum drm_connector_status
> dw_hdmi_phy_read_hpd(struct dw_hdmi *hdmi, connector_status_connected :
> connector_status_disconnected;
> }
>
> +static void dw_hdmi_phy_update_hpd(struct dw_hdmi *hdmi, void *data,
> + bool force, bool disabled, bool rxsense)
> +{
> + if (force || disabled || !rxsense)
> + hdmi->phy_mask |= HDMI_PHY_RX_SENSE;
> + else
> + hdmi->phy_mask &= ~HDMI_PHY_RX_SENSE;
> +}
> +
> +static void dw_hdmi_phy_setup_hpd(struct dw_hdmi *hdmi, void *data)
> +{
> + /* setup HPD and RXSENSE interrupt polarity */
> + hdmi_writeb(hdmi, HDMI_PHY_HPD | HDMI_PHY_RX_SENSE, HDMI_PHY_POL0);
> +}
> +
> +static void dw_hdmi_phy_configure_hpd(struct dw_hdmi *hdmi, void *data)
> +{
> + /* enable cable hot plug irq */
> + hdmi_writeb(hdmi, hdmi->phy_mask, HDMI_PHY_MASK0);
> +}
> +
> +static void dw_hdmi_phy_clear_hpd(struct dw_hdmi *hdmi, void *data)
> +{
> + /* Clear Hotplug interrupts */
> + hdmi_writeb(hdmi, HDMI_IH_PHY_STAT0_HPD | HDMI_IH_PHY_STAT0_RX_SENSE,
> + HDMI_IH_PHY_STAT0);
> +}
> +
> +static void dw_hdmi_phy_unmute_hpd(struct dw_hdmi *hdmi, void *data)
> +{
> + /* Unmute Hotplug interrupts */
> + hdmi_writeb(hdmi, ~(HDMI_IH_PHY_STAT0_HPD |
HDMI_IH_PHY_STAT0_RX_SENSE),
> + HDMI_IH_MUTE_PHY_STAT0);
> +}

Do we really need all those new operations ? It looks to me like a bit of
refactoring could help lowering the number of operations. We essentially need

- an init function called at probe time (or likely rather at runtime PM resume
time when we'll implement runtime PM)

- an interrupt enable/disable function roughly equivalent to
dw_hdmi_update_phy_mask()

- a read function to report the detection results called from
dw_hdmi_connector_detect()

> static const struct dw_hdmi_phy_ops dw_hdmi_synopsys_phy_ops = {
> .init = dw_hdmi_phy_init,
> .disable = dw_hdmi_phy_disable,
> .read_hpd = dw_hdmi_phy_read_hpd,
> + .update_hpd = dw_hdmi_phy_update_hpd,
> + .setup_hpd = dw_hdmi_phy_setup_hpd,
> + .configure_hpd = dw_hdmi_phy_configure_hpd,
> + .clear_hpd = dw_hdmi_phy_clear_hpd,
> + .unmute_hpd = dw_hdmi_phy_unmute_hpd,
> };
>
> /* ------------------------------------------------------------------------
> @@ -1507,11 +1547,12 @@ static int dw_hdmi_fb_registered(struct dw_hdmi
> *hdmi) HDMI_PHY_I2CM_CTLINT_ADDR);
>
> /* enable cable hot plug irq */
> - hdmi_writeb(hdmi, hdmi->phy_mask, HDMI_PHY_MASK0);
> + if (hdmi->phy.ops->configure_hpd)
> + hdmi->phy.ops->configure_hpd(hdmi, hdmi->phy.data);
>
> /* Clear Hotplug interrupts */
> - hdmi_writeb(hdmi, HDMI_IH_PHY_STAT0_HPD | HDMI_IH_PHY_STAT0_RX_SENSE,
> - HDMI_IH_PHY_STAT0);
> + if (hdmi->phy.ops->clear_hpd)
> + hdmi->phy.ops->clear_hpd(hdmi, hdmi->phy.data);

The probe function contains the same code. Let's inline this function into
probe, group all HPD-related initialization together and extract that into a
function to keep probe easy to read. I think you can do that in a separate
patch.

> return 0;
> }
> @@ -1622,13 +1663,14 @@ static void dw_hdmi_update_phy_mask(struct dw_hdmi
> *hdmi) {
> u8 old_mask = hdmi->phy_mask;
>
> - if (hdmi->force || hdmi->disabled || !hdmi->rxsense)
> - hdmi->phy_mask |= HDMI_PHY_RX_SENSE;
> - else
> - hdmi->phy_mask &= ~HDMI_PHY_RX_SENSE;
> + if (hdmi->phy.ops->update_hpd)
> + hdmi->phy.ops->update_hpd(hdmi, hdmi->phy.data,
> + hdmi->force, hdmi->disabled,
> + hdmi->rxsense);
>
> - if (old_mask != hdmi->phy_mask)
> - hdmi_writeb(hdmi, hdmi->phy_mask, HDMI_PHY_MASK0);
> + if (old_mask != hdmi->phy_mask &&

phy_mask isn't accessible to glue code, so this test will never be true with
vendor PHYs.

> + hdmi->phy.ops->configure_hpd)
> + hdmi->phy.ops->configure_hpd(hdmi, hdmi->phy.data);
> }
>
> static enum drm_connector_status
> @@ -1820,6 +1862,41 @@ static irqreturn_t dw_hdmi_hardirq(int irq, void
> *dev_id) return ret;
> }
>
> +void __dw_hdmi_setup_rx_sense(struct dw_hdmi *hdmi, bool hpd, bool
> rx_sense)
> +{
> + mutex_lock(&hdmi->mutex);
> +
> + if (!hdmi->disabled && !hdmi->force) {
> + /*
> + * If the RX sense status indicates we're disconnected,
> + * clear the software rxsense status.
> + */
> + if (!rx_sense)
> + hdmi->rxsense = false;
> +
> + /*
> + * Only set the software rxsense status when both
> + * rxsense and hpd indicates we're connected.
> + * This avoids what seems to be bad behaviour in
> + * at least iMX6S versions of the phy.
> + */
> + if (hpd)
> + hdmi->rxsense = true;

This contradicts the above comment, hdmi->rxsense is set back to true solely
based on the hpd parameter.

> +
> + dw_hdmi_update_power(hdmi);
> + dw_hdmi_update_phy_mask(hdmi);
> + }

I'd add a blank line here.

> + mutex_unlock(&hdmi->mutex);
> +}
> +
> +void dw_hdmi_setup_rx_sense(struct device *dev, bool hpd, bool rx_sense)
> +{
> + struct dw_hdmi *hdmi = dev_get_drvdata(dev);
> +
> + __dw_hdmi_setup_rx_sense(hdmi, hpd, rx_sense);
> +}
> +EXPORT_SYMBOL_GPL(dw_hdmi_setup_rx_sense);
> +
> static irqreturn_t dw_hdmi_irq(int irq, void *dev_id)
> {
> struct dw_hdmi *hdmi = dev_id;
> @@ -1852,30 +1929,10 @@ static irqreturn_t dw_hdmi_irq(int irq, void
> *dev_id) * ask the source to re-read the EDID.
> */
> if (intr_stat &
> - (HDMI_IH_PHY_STAT0_RX_SENSE | HDMI_IH_PHY_STAT0_HPD)) {
> - mutex_lock(&hdmi->mutex);
> - if (!hdmi->disabled && !hdmi->force) {
> - /*
> - * If the RX sense status indicates we're
disconnected,
> - * clear the software rxsense status.
> - */
> - if (!(phy_stat & HDMI_PHY_RX_SENSE))
> - hdmi->rxsense = false;
> -
> - /*
> - * Only set the software rxsense status when both
> - * rxsense and hpd indicates we're connected.
> - * This avoids what seems to be bad behaviour in
> - * at least iMX6S versions of the phy.
> - */
> - if (phy_stat & HDMI_PHY_HPD)
> - hdmi->rxsense = true;
> -
> - dw_hdmi_update_power(hdmi);
> - dw_hdmi_update_phy_mask(hdmi);
> - }
> - mutex_unlock(&hdmi->mutex);
> - }
> + (HDMI_IH_PHY_STAT0_RX_SENSE | HDMI_IH_PHY_STAT0_HPD))

Is this right ? If your SoC implements a custom HPD mechanism, does it still
rely on the standard RX SENSE and HPD interrupts ? In particular, this
function still writes the HDMI_IH_MUTE_PHY_STAT0 register directly, while
you've extracted a write to the same register in the probe function into a PHY
operation.

> + __dw_hdmi_setup_rx_sense(hdmi,
> + phy_stat & HDMI_PHY_HPD,
> + phy_stat & HDMI_PHY_RX_SENSE);
>
> if (intr_stat & HDMI_IH_PHY_STAT0_HPD) {
> dev_dbg(hdmi->dev, "EVENT=%s\n",
> @@ -2146,11 +2203,12 @@ static int dw_hdmi_detect_phy(struct dw_hdmi *hdmi)
> * Configure registers related to HDMI interrupt
> * generation before registering IRQ.
> */
> - hdmi_writeb(hdmi, HDMI_PHY_HPD | HDMI_PHY_RX_SENSE, HDMI_PHY_POL0);
> + if (hdmi->phy.ops->setup_hpd)
> + hdmi->phy.ops->setup_hpd(hdmi, hdmi->phy.data);
>
> /* Clear Hotplug interrupts */
> - hdmi_writeb(hdmi, HDMI_IH_PHY_STAT0_HPD | HDMI_IH_PHY_STAT0_RX_SENSE,
> - HDMI_IH_PHY_STAT0);
> + if (hdmi->phy.ops->clear_hpd)
> + hdmi->phy.ops->clear_hpd(hdmi, hdmi->phy.data);
>
> hdmi->bridge.driver_private = hdmi;
> hdmi->bridge.funcs = &dw_hdmi_bridge_funcs;
> @@ -2163,8 +2221,8 @@ static int dw_hdmi_detect_phy(struct dw_hdmi *hdmi)
> goto err_iahb;
>
> /* Unmute interrupts */
> - hdmi_writeb(hdmi, ~(HDMI_IH_PHY_STAT0_HPD |
HDMI_IH_PHY_STAT0_RX_SENSE),
> - HDMI_IH_MUTE_PHY_STAT0);
> + if (hdmi->phy.ops->unmute_hpd)
> + hdmi->phy.ops->unmute_hpd(hdmi, hdmi->phy.data);
>
> memset(&pdevinfo, 0, sizeof(pdevinfo));
> pdevinfo.parent = dev;
> diff --git a/include/drm/bridge/dw_hdmi.h b/include/drm/bridge/dw_hdmi.h
> index 8c0cc13..d72403f 100644
> --- a/include/drm/bridge/dw_hdmi.h
> +++ b/include/drm/bridge/dw_hdmi.h
> @@ -64,6 +64,12 @@ struct dw_hdmi_phy_ops {
> struct drm_display_mode *mode);
> void (*disable)(struct dw_hdmi *hdmi, void *data);
> enum drm_connector_status (*read_hpd)(struct dw_hdmi *hdmi, void
*data);
> + void (*update_hpd)(struct dw_hdmi *hdmi, void *data,
> + bool force, bool disabled, bool rxsense);
> + void (*setup_hpd)(struct dw_hdmi *hdmi, void *data);
> + void (*configure_hpd)(struct dw_hdmi *hdmi, void *data);
> + void (*clear_hpd)(struct dw_hdmi *hdmi, void *data);
> + void (*unmute_hpd)(struct dw_hdmi *hdmi, void *data);

That's quite a lot of new operations. I think we need documentation :-)

> };
>
> struct dw_hdmi_plat_data {
> @@ -93,6 +99,8 @@ int dw_hdmi_probe(struct platform_device *pdev,
> int dw_hdmi_bind(struct platform_device *pdev, struct drm_encoder *encoder,
> const struct dw_hdmi_plat_data *plat_data);
>
> +void dw_hdmi_setup_rx_sense(struct device *dev, bool hpd, bool rx_sense);
> +
> void dw_hdmi_set_sample_rate(struct dw_hdmi *hdmi, unsigned int rate);
> void dw_hdmi_audio_enable(struct dw_hdmi *hdmi);
> void dw_hdmi_audio_disable(struct dw_hdmi *hdmi);

--
Regards,

Laurent Pinchart