[Intel-gfx] [PATCH v2] drm/i915: add i915 specific connector debugfs file for DPCD

[R, Durgadoss]

>-----Original Message-----
>From: Intel-gfx [mailto:intel-gfx-bounces at lists.freedesktop.org] On Behalf Of Jani Nikula
>Sent: Wednesday, April 1, 2015 1:45 PM
>To: intel-gfx at lists.freedesktop.org
>Cc: Nikula, Jani
>Subject: [Intel-gfx] [PATCH v2] drm/i915: add i915 specific connector debugfs file for DPCD
>
>Occasionally it would be interesting to read some of the DPCD registers
>for debug purposes, without having to resort to logging. Add an i915
>specific i915_dpcd debugfs file for DP and eDP connectors to dump parts
>of the DPCD. Currently the DPCD addresses to be dumped are statically
>configured, and more can be added trivially.
>
>The implementation also makes it relatively easy to add other i915 and
>connector specific debugfs files in the future, as necessary.
>
>This is currently i915 specific just because there's no generic way to
>do AUX transactions given just a drm_connector. However it's all pretty
>straightforward to port to other drivers.
>
>v2: Add more DPCD registers to dump.
>

Tested-by: Durgadoss R <durgadoss.r at intel.com>

Thanks,
Durga

>Signed-off-by: Jani Nikula <jani.nikula at intel.com>
>---
> drivers/gpu/drm/i915/i915_debugfs.c | 96 +++++++++++++++++++++++++++++++++++++
> drivers/gpu/drm/i915/i915_drv.h     |  1 +
> drivers/gpu/drm/i915/intel_dp.c     |  2 +
> 3 files changed, 99 insertions(+)
>
>diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
>index 007c7d7d8295..7164aa7d5fd3 100644
>--- a/drivers/gpu/drm/i915/i915_debugfs.c
>+++ b/drivers/gpu/drm/i915/i915_debugfs.c
>@@ -4780,3 +4780,99 @@ void i915_debugfs_cleanup(struct drm_minor *minor)
> 		drm_debugfs_remove_files(info_list, 1, minor);
> 	}
> }
>+
>+struct dpcd_block {
>+	/* DPCD dump start address. */
>+	unsigned int offset;
>+	/* DPCD dump end address, inclusive. If unset, .size will be used. */
>+	unsigned int end;
>+	/* DPCD dump size. Used if .end is unset. If unset, defaults to 1. */
>+	size_t size;
>+	/* Only valid for eDP. */
>+	bool edp;
>+};
>+
>+static const struct dpcd_block i915_dpcd_debug[] = {
>+	{ .offset = DP_DPCD_REV, .size = DP_RECEIVER_CAP_SIZE },
>+	{ .offset = DP_PSR_SUPPORT, .end = DP_PSR_CAPS },
>+	{ .offset = DP_DOWNSTREAM_PORT_0, .size = 16 },
>+	{ .offset = DP_LINK_BW_SET, .end = DP_EDP_CONFIGURATION_SET },
>+	{ .offset = DP_SINK_COUNT, .end = DP_ADJUST_REQUEST_LANE2_3 },
>+	{ .offset = DP_SET_POWER },
>+	{ .offset = DP_EDP_DPCD_REV },
>+	{ .offset = DP_EDP_GENERAL_CAP_1, .end = DP_EDP_GENERAL_CAP_3 },
>+	{ .offset = DP_EDP_DISPLAY_CONTROL_REGISTER, .end =
>DP_EDP_BACKLIGHT_FREQ_CAP_MAX_LSB },
>+	{ .offset = DP_EDP_DBC_MINIMUM_BRIGHTNESS_SET, .end =
>DP_EDP_DBC_MAXIMUM_BRIGHTNESS_SET },
>+};
>+
>+static int i915_dpcd_show(struct seq_file *m, void *data)
>+{
>+	struct drm_connector *connector = m->private;
>+	struct intel_dp *intel_dp =
>+		enc_to_intel_dp(&intel_attached_encoder(connector)->base);
>+	uint8_t buf[16];
>+	ssize_t err;
>+	int i;
>+
>+	for (i = 0; i < ARRAY_SIZE(i915_dpcd_debug); i++) {
>+		const struct dpcd_block *b = &i915_dpcd_debug[i];
>+		size_t size = b->end ? b->end - b->offset + 1 : (b->size ?: 1);
>+
>+		if (b->edp &&
>+		    connector->connector_type != DRM_MODE_CONNECTOR_eDP)
>+			continue;
>+
>+		/* low tech for now */
>+		if (WARN_ON(size > sizeof(buf)))
>+			continue;
>+
>+		err = drm_dp_dpcd_read(&intel_dp->aux, b->offset, buf, size);
>+		if (err <= 0) {
>+			DRM_ERROR("dpcd read (%zu bytes at %u) failed (%zd)\n",
>+				  size, b->offset, err);
>+			continue;
>+		}
>+
>+		seq_printf(m, "%04x: %*ph\n", b->offset, (int) size, buf);
>+	};
>+
>+	return 0;
>+}
>+
>+static int i915_dpcd_open(struct inode *inode, struct file *file)
>+{
>+	return single_open(file, i915_dpcd_show, inode->i_private);
>+}
>+
>+static const struct file_operations i915_dpcd_fops = {
>+	.owner = THIS_MODULE,
>+	.open = i915_dpcd_open,
>+	.read = seq_read,
>+	.llseek = seq_lseek,
>+	.release = single_release,
>+};
>+
>+/**
>+ * i915_debugfs_connector_add - add i915 specific connector debugfs files
>+ * @connector: pointer to a registered drm_connector
>+ *
>+ * Cleanup will be done by drm_connector_unregister() through a call to
>+ * drm_debugfs_connector_remove().
>+ *
>+ * Returns 0 on success, negative error codes on error.
>+ */
>+int i915_debugfs_connector_add(struct drm_connector *connector)
>+{
>+	struct dentry *root = connector->debugfs_entry;
>+
>+	/* The connector must have been registered beforehands. */
>+	if (!root)
>+		return -ENODEV;
>+
>+	if (connector->connector_type == DRM_MODE_CONNECTOR_DisplayPort ||
>+	    connector->connector_type == DRM_MODE_CONNECTOR_eDP)
>+		debugfs_create_file("i915_dpcd", S_IRUGO, root, connector,
>+				    &i915_dpcd_fops);
>+
>+	return 0;
>+}
>diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
>index aadada5a3fe9..868f26780115 100644
>--- a/drivers/gpu/drm/i915/i915_drv.h
>+++ b/drivers/gpu/drm/i915/i915_drv.h
>@@ -3011,6 +3011,7 @@ int i915_verify_lists(struct drm_device *dev);
> /* i915_debugfs.c */
> int i915_debugfs_init(struct drm_minor *minor);
> void i915_debugfs_cleanup(struct drm_minor *minor);
>+int i915_debugfs_connector_add(struct drm_connector *connector);
> #ifdef CONFIG_DEBUG_FS
> void intel_display_crc_init(struct drm_device *dev);
> #else
>diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
>index 7936155acbe8..f91ce9e94aa6 100644
>--- a/drivers/gpu/drm/i915/intel_dp.c
>+++ b/drivers/gpu/drm/i915/intel_dp.c
>@@ -5569,6 +5569,8 @@ intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
> 		I915_WRITE(PEG_BAND_GAP_DATA, (temp & ~0xf) | 0xd);
> 	}
>
>+	i915_debugfs_connector_add(connector);
>+
> 	return true;
> }
>
>--
>2.1.4
>
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