[PATCH RFC 27/46] imx-drm: convert to componentised device support

Philipp Zabel
2014-01-07T16:29:55Z

Am Dienstag, den 07.01.2014, 08:30 -0700 schrieb Eric Nelson:
> Hi Philipp,
>
> On 01/07/2014 04:29 AM, Philipp Zabel wrote:
> > Am Montag, den 06.01.2014, 19:31 -0700 schrieb Eric Nelson:
> >> Hi Russell,
> >>
> >> On 01/06/2014 10:46 AM, Russell King - ARM Linux wrote:
> >>> On Mon, Jan 06, 2014 at 06:41:28PM +0100, Philipp Zabel wrote:
> >>>> Hi Eric,
> >>>>
> >>>> Am Freitag, den 03.01.2014, 12:14 -0700 schrieb Eric Nelson:
> >>>>> This is an issue we've seen before. The SABRE Lite board has
> >>>>> a voltage divider on the HPD pins and some monitors (esp. DVI
> >>>>> monitors) either don't drive things high enough to assert HPD or
> >>>>> bounce with connect/disconnect.
> >>>>
> >>>> Yes, I used a DVI monitor.
> >>>>
> >>>>> We've instrumented our 3.0.35 kernels to use the RX_SENSE bits
> >>>>> instead.
> >>>>
> >>>> Reacting to RX_SENSE0 instead of HPD seems to work.
> >>>
> >>> However, it's non-compliant, because HPD can be lowered and raised by
> >>> the sink when it changes its EDID data (eg, because you're connected
> >>> through a switch and the routing has been changed.)
> >>>
> >>> So, reacting to RX_SENSE0 instead of HPD has to be a work-around enabled
> >>> only for those boards which are broken in this regard.
> >>>
> >>
> >> I understand. We'll need to carry some patches for a while though,
> >> since there are lots of these boards in the wild.
> >
> > Could you point me to your changes? Maybe this could be added to
> > mainline as a quirk enabled by a device tree property on sabrelite only.
> >
>
> We only have them for 3.0.35 at the moment.
>
> Here's the patch to use RXSENSE instead of HPD
> https://github.com/boundarydevices/linux-imx6/commit/c0439e262bb6c23887d96466b2ab7916aa0488d9
>
> A follow-up patch disables the disconnect detection entirely
> unless requested:
> https://github.com/boundarydevices/linux-imx6/commit/d9cd79d11ff9f7a7f89cbc94b68757b67cdfe5fc

Thanky you. This is what I came up with so far:

From: Philipp Zabel <p.zabel@pengutronix.de>
Subject: [PATCH 1/2] staging: imx-hdmi: use RX_SENSE0 for plug detection if
HPD is unreliable

On some boards HPD might not reliably detect DVI monitors. Allow to use
RX_SENSE0 as a workaround.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
---
drivers/staging/imx-drm/imx-hdmi.c | 45 +++++++++++++++++++++++++++++---------
1 file changed, 35 insertions(+), 10 deletions(-)

diff --git a/drivers/staging/imx-drm/imx-hdmi.c b/drivers/staging/imx-drm/imx-hdmi.c
index 7779337..cc305f3 100644
--- a/drivers/staging/imx-drm/imx-hdmi.c
+++ b/drivers/staging/imx-drm/imx-hdmi.c
@@ -139,6 +139,7 @@ struct imx_hdmi {

struct regmap *regmap;
struct i2c_adapter *ddc;
+ bool hpd_unreliable;
void __iomem *regs;

unsigned int sample_rate;
@@ -1309,6 +1310,14 @@ static int imx_hdmi_setup(struct imx_hdmi *hdmi, struct drm_display_mode *mode)
/* Wait until we are registered to enable interrupts */
static int imx_hdmi_fb_registered(struct imx_hdmi *hdmi)
{
+ int stat_bit = HDMI_IH_PHY_STAT0_HPD;
+ int mask_bits = ~HDMI_PHY_HPD;
+
+ if (hdmi->hpd_unreliable) {
+ stat_bit = HDMI_IH_PHY_STAT0_RX_SENSE0;
+ mask_bits = ~HDMI_PHY_RX_SENSE0;
+ }
+
hdmi_writeb(hdmi, HDMI_PHY_I2CM_INT_ADDR_DONE_POL,
HDMI_PHY_I2CM_INT_ADDR);

@@ -1317,10 +1326,10 @@ static int imx_hdmi_fb_registered(struct imx_hdmi *hdmi)
HDMI_PHY_I2CM_CTLINT_ADDR);

/* enable cable hot plug irq */
- hdmi_writeb(hdmi, (u8)~HDMI_PHY_RX_SENSE0, HDMI_PHY_MASK0);
+ hdmi_writeb(hdmi, (u8)mask_bits, HDMI_PHY_MASK0);

/* Clear Hotplug interrupts */
- hdmi_writeb(hdmi, HDMI_IH_PHY_STAT0_RX_SENSE0, HDMI_IH_PHY_STAT0);
+ hdmi_writeb(hdmi, stat_bit, HDMI_IH_PHY_STAT0);

return 0;
}
@@ -1524,25 +1533,32 @@ static irqreturn_t imx_hdmi_hardirq(int irq, void *dev_id)
static irqreturn_t imx_hdmi_irq(int irq, void *dev_id)
{
struct imx_hdmi *hdmi = dev_id;
+ int stat_bit = HDMI_IH_PHY_STAT0_HPD;
+ int pol_bit = HDMI_PHY_HPD;
u8 intr_stat;
u8 phy_int_pol;

+ if (hdmi->hpd_unreliable) {
+ stat_bit = HDMI_IH_PHY_STAT0_RX_SENSE0;
+ pol_bit = HDMI_PHY_RX_SENSE0;
+ }
+
intr_stat = hdmi_readb(hdmi, HDMI_IH_PHY_STAT0);

phy_int_pol = hdmi_readb(hdmi, HDMI_PHY_POL0);

- if (intr_stat & HDMI_IH_PHY_STAT0_RX_SENSE0) {
- if (phy_int_pol & HDMI_PHY_RX_SENSE0) {
+ if (intr_stat & stat_bit) {
+ if (phy_int_pol & pol_bit) {
dev_dbg(hdmi->dev, "EVENT=plugin\n");

- hdmi_modb(hdmi, 0, HDMI_PHY_RX_SENSE0, HDMI_PHY_POL0);
+ hdmi_modb(hdmi, 0, pol_bit, HDMI_PHY_POL0);

hdmi->connector_status = connector_status_connected;
imx_hdmi_poweron(hdmi);
} else {
dev_dbg(hdmi->dev, "EVENT=plugout\n");

- hdmi_modb(hdmi, HDMI_PHY_RX_SENSE0, HDMI_PHY_RX_SENSE0, HDMI_PHY_POL0);
+ hdmi_modb(hdmi, pol_bit, pol_bit, HDMI_PHY_POL0);

hdmi->connector_status = connector_status_disconnected;
imx_hdmi_poweroff(hdmi);
@@ -1551,7 +1567,7 @@ static irqreturn_t imx_hdmi_irq(int irq, void *dev_id)
}

hdmi_writeb(hdmi, intr_stat, HDMI_IH_PHY_STAT0);
- hdmi_writeb(hdmi, ~HDMI_IH_PHY_STAT0_RX_SENSE0, HDMI_IH_MUTE_PHY_STAT0);
+ hdmi_writeb(hdmi, ~stat_bit, HDMI_IH_MUTE_PHY_STAT0);

return IRQ_HANDLED;
}
@@ -1611,6 +1627,7 @@ static int imx_hdmi_bind(struct device *dev, struct device *master, void *data)
struct device_node *ddc_node;
struct imx_hdmi *hdmi;
struct resource *iores;
+ int pol_bit, stat_bit;
int ret, irq;

hdmi = devm_kzalloc(dev, sizeof(*hdmi), GFP_KERNEL);
@@ -1703,14 +1720,22 @@ static int imx_hdmi_bind(struct device *dev, struct device *master, void *data)
*/
hdmi_init_clk_regenerator(hdmi);

+ pol_bit = HDMI_PHY_HPD;
+ stat_bit = HDMI_IH_PHY_STAT0_HPD;
+ hdmi->hpd_unreliable = of_property_read_bool(np, "hpd-unreliable");
+ if (hdmi->hpd_unreliable) {
+ pol_bit = HDMI_PHY_RX_SENSE0;
+ stat_bit = HDMI_IH_PHY_STAT0_RX_SENSE0;
+ }
+
/*
* Configure registers related to HDMI interrupt
* generation before registering IRQ.
*/
- hdmi_writeb(hdmi, HDMI_PHY_RX_SENSE0, HDMI_PHY_POL0);
+ hdmi_writeb(hdmi, pol_bit, HDMI_PHY_POL0);

/* Clear Hotplug interrupts */
- hdmi_writeb(hdmi, HDMI_IH_PHY_STAT0_RX_SENSE0, HDMI_IH_PHY_STAT0);
+ hdmi_writeb(hdmi, stat_bit, HDMI_IH_PHY_STAT0);

ret = imx_hdmi_fb_registered(hdmi);
if (ret)
@@ -1721,7 +1746,7 @@ static int imx_hdmi_bind(struct device *dev, struct device *master, void *data)
goto err_iahb;

/* Unmute interrupts */
- hdmi_writeb(hdmi, ~HDMI_IH_PHY_STAT0_RX_SENSE0, HDMI_IH_MUTE_PHY_STAT0);
+ hdmi_writeb(hdmi, ~stat_bit, HDMI_IH_MUTE_PHY_STAT0);

ret = snd_dw_hdmi_probe(&hdmi->audio, dev, hdmi->regs, irq, hdmi);
if (ret)
--
1.8.5.2

regards
Philipp