diff options
| -rw-r--r-- | drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 116 |
1 files changed, 100 insertions, 16 deletions
diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c index 66bd66bad44c..7c8d5d316f04 100644 --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c @@ -19,6 +19,7 @@ #include <linux/module.h> #include <linux/mutex.h> #include <linux/of_device.h> +#include <linux/pinctrl/consumer.h> #include <linux/regmap.h> #include <linux/dma-mapping.h> #include <linux/spinlock.h> @@ -170,6 +171,10 @@ struct dw_hdmi { bool sink_is_hdmi; bool sink_has_audio; + struct pinctrl *pinctrl; + struct pinctrl_state *default_state; + struct pinctrl_state *unwedge_state; + struct mutex mutex; /* for state below and previous_mode */ enum drm_connector_force force; /* mutex-protected force state */ bool disabled; /* DRM has disabled our bridge */ @@ -248,11 +253,82 @@ static void dw_hdmi_i2c_init(struct dw_hdmi *hdmi) HDMI_IH_MUTE_I2CM_STAT0); } +static bool dw_hdmi_i2c_unwedge(struct dw_hdmi *hdmi) +{ + /* If no unwedge state then give up */ + if (IS_ERR(hdmi->unwedge_state)) + return false; + + dev_info(hdmi->dev, "Attempting to unwedge stuck i2c bus\n"); + + /* + * This is a huge hack to workaround a problem where the dw_hdmi i2c + * bus could sometimes get wedged. Once wedged there doesn't appear + * to be any way to unwedge it (including the HDMI_I2CM_SOFTRSTZ) + * other than pulsing the SDA line. + * + * We appear to be able to pulse the SDA line (in the eyes of dw_hdmi) + * by: + * 1. Remux the pin as a GPIO output, driven low. + * 2. Wait a little while. 1 ms seems to work, but we'll do 10. + * 3. Immediately jump to remux the pin as dw_hdmi i2c again. + * + * At the moment of remuxing, the line will still be low due to its + * recent stint as an output, but then it will be pulled high by the + * (presumed) external pullup. dw_hdmi seems to see this as a rising + * edge and that seems to get it out of its jam. + * + * This wedging was only ever seen on one TV, and only on one of + * its HDMI ports. It happened when the TV was powered on while the + * device was plugged in. A scope trace shows the TV bringing both SDA + * and SCL low, then bringing them both back up at roughly the same + * time. Presumably this confuses dw_hdmi because it saw activity but + * no real STOP (maybe it thinks there's another master on the bus?). + * Giving it a clean rising edge of SDA while SCL is already high + * presumably makes dw_hdmi see a STOP which seems to bring dw_hdmi out + * of its stupor. + * + * Note that after coming back alive, transfers seem to immediately + * resume, so if we unwedge due to a timeout we should wait a little + * longer for our transfer to finish, since it might have just started + * now. + */ + pinctrl_select_state(hdmi->pinctrl, hdmi->unwedge_state); + msleep(10); + pinctrl_select_state(hdmi->pinctrl, hdmi->default_state); + + return true; +} + +static int dw_hdmi_i2c_wait(struct dw_hdmi *hdmi) +{ + struct dw_hdmi_i2c *i2c = hdmi->i2c; + int stat; + + stat = wait_for_completion_timeout(&i2c->cmp, HZ / 10); + if (!stat) { + /* If we can't unwedge, return timeout */ + if (!dw_hdmi_i2c_unwedge(hdmi)) + return -EAGAIN; + + /* We tried to unwedge; give it another chance */ + stat = wait_for_completion_timeout(&i2c->cmp, HZ / 10); + if (!stat) + return -EAGAIN; + } + + /* Check for error condition on the bus */ + if (i2c->stat & HDMI_IH_I2CM_STAT0_ERROR) + return -EIO; + + return 0; +} + static int dw_hdmi_i2c_read(struct dw_hdmi *hdmi, unsigned char *buf, unsigned int length) { struct dw_hdmi_i2c *i2c = hdmi->i2c; - int stat; + int ret; if (!i2c->is_regaddr) { dev_dbg(hdmi->dev, "set read register address to 0\n"); @@ -271,13 +347,9 @@ static int dw_hdmi_i2c_read(struct dw_hdmi *hdmi, hdmi_writeb(hdmi, HDMI_I2CM_OPERATION_READ, HDMI_I2CM_OPERATION); - stat = wait_for_completion_timeout(&i2c->cmp, HZ / 10); - if (!stat) - return -EAGAIN; - - /* Check for error condition on the bus */ - if (i2c->stat & HDMI_IH_I2CM_STAT0_ERROR) - return -EIO; + ret = dw_hdmi_i2c_wait(hdmi); + if (ret) + return ret; *buf++ = hdmi_readb(hdmi, HDMI_I2CM_DATAI); } @@ -290,7 +362,7 @@ static int dw_hdmi_i2c_write(struct dw_hdmi *hdmi, unsigned char *buf, unsigned int length) { struct dw_hdmi_i2c *i2c = hdmi->i2c; - int stat; + int ret; if (!i2c->is_regaddr) { /* Use the first write byte as register address */ @@ -308,13 +380,9 @@ static int dw_hdmi_i2c_write(struct dw_hdmi *hdmi, hdmi_writeb(hdmi, HDMI_I2CM_OPERATION_WRITE, HDMI_I2CM_OPERATION); - stat = wait_for_completion_timeout(&i2c->cmp, HZ / 10); - if (!stat) - return -EAGAIN; - - /* Check for error condition on the bus */ - if (i2c->stat & HDMI_IH_I2CM_STAT0_ERROR) - return -EIO; + ret = dw_hdmi_i2c_wait(hdmi); + if (ret) + return ret; } return 0; @@ -2615,6 +2683,22 @@ __dw_hdmi_probe(struct platform_device *pdev, /* If DDC bus is not specified, try to register HDMI I2C bus */ if (!hdmi->ddc) { + /* Look for (optional) stuff related to unwedging */ + hdmi->pinctrl = devm_pinctrl_get(dev); + if (!IS_ERR(hdmi->pinctrl)) { + hdmi->unwedge_state = + pinctrl_lookup_state(hdmi->pinctrl, "unwedge"); + hdmi->default_state = + pinctrl_lookup_state(hdmi->pinctrl, "default"); + + if (IS_ERR(hdmi->default_state) && + !IS_ERR(hdmi->unwedge_state)) { + dev_warn(dev, + "Unwedge requires default pinctrl\n"); + hdmi->unwedge_state = ERR_PTR(-ENODEV); + } + } + hdmi->ddc = dw_hdmi_i2c_adapter(hdmi); if (IS_ERR(hdmi->ddc)) hdmi->ddc = NULL; |