Hi,
On Wed, Sep 10, 2025 at 11:34 AM John Ripple <john.rip...@keysight.com> wrote:
>
> @@ -221,6 +236,23 @@ static const struct regmap_config
> ti_sn65dsi86_regmap_config = {
> .max_register = 0xFF,
> };
>
> +static int ti_sn65dsi86_read_u8(struct ti_sn65dsi86 *pdata, unsigned int reg,
> + u8 *val)
nit: indentation is slightly off. checkpatch --strict yells:
CHECK: Alignment should match open parenthesis
#79: FILE: drivers/gpu/drm/bridge/ti-sn65dsi86.c:240:
+static int ti_sn65dsi86_read_u8(struct ti_sn65dsi86 *pdata, unsigned int reg,
+ u8 *val)
> @@ -413,6 +446,13 @@ static int __maybe_unused ti_sn65dsi86_resume(struct
> device *dev)
> if (pdata->refclk)
> ti_sn65dsi86_enable_comms(pdata, NULL);
>
> + if (client->irq) {
> + ret = regmap_update_bits(pdata->regmap, SN_IRQ_EN_REG, IRQ_EN,
> + IRQ_EN);
nit: checkpatch --strict yells:
CHECK: Alignment should match open parenthesis
#112: FILE: drivers/gpu/drm/bridge/ti-sn65dsi86.c:451:
+ ret = regmap_update_bits(pdata->regmap, SN_IRQ_EN_REG, IRQ_EN,
+ IRQ_EN);
> @@ -1219,11 +1262,32 @@ static void ti_sn_bridge_hpd_enable(struct drm_bridge
> *bridge)
> */
>
> pm_runtime_get_sync(pdata->dev);
> +
> + mutex_lock(&pdata->hpd_mutex);
> + if (client->irq) {
> + /* Enable HPD events. */
> + val = HPD_REMOVAL_EN | HPD_INSERTION_EN;
> + ret = regmap_update_bits(pdata->regmap, SN_IRQ_EVENTS_EN_REG,
> val, val);
nit: regmap_set_bits() ?
...and then you don't need the "val" temporary variable.
> + if (ret)
> + pr_err("Failed to enable HPD events: %d\n", ret);
> + }
> + pdata->hpd_enabled = true;
> + mutex_unlock(&pdata->hpd_mutex);
So I _think_ you only need the mutex around the set of "hpd_enabled".
Really the only things you're trying to do are:
* Make sure that by the time ti_sn_bridge_hpd_disable() returns that
no more HPD callback will be made
* Make sure that after ti_sn_bridge_hpd_enable() is called that the
next interrupt will notice the update.
So I'd make the enable case look something like this:
mutex_lock(&pdata->hpd_mutex);
pdata->hpd_enabled = true;
mutex_unlock(&pdata->hpd_mutex);
if (client->irq) {
/* Enable HPD events. */
val = HPD_REMOVAL_EN | HPD_INSERTION_EN;
ret = regmap_update_bits(pdata->regmap, SN_IRQ_EVENTS_EN_REG, val, val);
if (ret)
pr_err("Failed to enable HPD events: %d\n", ret);
}
...and the disable case:
if (client->irq) {
/* Disable HPD events. */
regmap_write(pdata->regmap, SN_IRQ_EVENTS_EN_REG, 0);
regmap_update_bits(pdata->regmap, SN_IRQ_EN_REG, IRQ_EN, 0);
}
mutex_lock(&pdata->hpd_mutex);
pdata->hpd_enabled = false;
mutex_unlock(&pdata->hpd_mutex);
Does that seem reasonable?
> @@ -1309,6 +1373,44 @@ static int ti_sn_bridge_parse_dsi_host(struct
> ti_sn65dsi86 *pdata)
> return 0;
> }
>
> +static irqreturn_t ti_sn_bridge_interrupt(int irq, void *private)
> +{
> + struct ti_sn65dsi86 *pdata = private;
> + struct drm_device *dev = pdata->bridge.dev;
> + u8 status;
> + int ret;
> + bool hpd_event = false;
> +
> + mutex_lock(&pdata->hpd_mutex);
> + if (!pdata->hpd_enabled) {
> + mutex_unlock(&pdata->hpd_mutex);
> + return IRQ_HANDLED;
> + }
I also think you _always_ want to Ack all status interrupts so there's
no way you could end up with an interrupt storm, so you shouldn't do
this early return.
> + ret = ti_sn65dsi86_read_u8(pdata, SN_IRQ_STATUS_REG, &status);
> + if (ret)
> + pr_err("Failed to read IRQ status: %d\n", ret);
> + else
> + hpd_event = status & (HPD_REMOVAL_STATUS |
> HPD_INSERTION_STATUS);
> +
> + if (status) {
> + drm_dbg(dev, "(SN_IRQ_STATUS_REG = %#x)\n", status);
> + ret = regmap_write(pdata->regmap, SN_IRQ_STATUS_REG, status);
> + if (ret)
> + pr_err("Failed to clear IRQ status: %d\n", ret);
> + } else {
> + mutex_unlock(&pdata->hpd_mutex);
> + return IRQ_NONE;
> + }
> +
> + /* Only send the HPD event if we are bound with a device. */
> + if (dev && hpd_event)
> + drm_kms_helper_hotplug_event(dev);
> + mutex_unlock(&pdata->hpd_mutex);
I think you only want the mutex to protect your checking of hpd_mutex
and sending the "drm_kms_helper_hotplug_event()". I don't think you
need it for the whole IRQ routine. AKA:
mutex_lock(&pdata->hpd_mutex);
if (hpd_event && pdata->hpd_enabled)
drm_kms_helper_hotplug_event(dev);
mutex_unlock(&pdata->hpd_mutex);
...and you don't need to check for "dev" being NULL because there's no
way "hpd_enabled" could be true with "dev" being NULL. At least this
is my assumption that the core DRM framework won't detach a bridge
while HPD is enabled. If nothing else, I guess you could call
ti_sn_bridge_hpd_disable() from ti_sn_bridge_detach()
> @@ -1971,6 +2075,28 @@ static int ti_sn65dsi86_probe(struct i2c_client
> *client)
> if (strncmp(id_buf, "68ISD ", ARRAY_SIZE(id_buf)))
> return dev_err_probe(dev, -EOPNOTSUPP, "unsupported device
> id\n");
>
> + if (client->irq) {
> + ret = devm_request_threaded_irq(pdata->dev, client->irq, NULL,
> + ti_sn_bridge_interrupt,
> + IRQF_TRIGGER_RISING |
> + IRQF_TRIGGER_FALLING |
> + IRQF_ONESHOT,
> + "ti_sn65dsi86", pdata);
> +
> + if (ret) {
> + return dev_err_probe(dev, ret,
> + "failed to request interrupt\n");
> + }
> +
> + /*
> + * Cleaning status register at probe is needed because if the
> irq is
> + * already high, the rising/falling condition will never occur
> + */
> + ret = regmap_write(pdata->regmap, SN_IRQ_STATUS_REG, 0xFF);
> + if (ret)
> + pr_warn("Failed to clear IRQ initial state: %d\n",
> ret);
Actually, wait. Why do you want "rising" and "falling". Isn't this a
level-triggered interrupt? Then you also don't need this bogus clear
of interrupts here...
...and also, I seem to recall it's usually better to not specify a
type here and rely on the type in the device tree. I seem to remember
there being some weird corner cases (maybe around remove / reprobe or
maybe about deferred probes?) if an interrupt type is specified in
both code and device tree and those types don't match...
-Doug
