On Wed, 1 Apr 2015 11:15:21 +0300
Jani Nikula <jani.nikula@xxxxxxxxx> wrote:
> 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.
>
> Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
Reviewed-by: Bob Paauwe <bob.j.paauwe@xxxxxxxxx>
> ---
> 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;
> }
>
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