Hi Anshuman,

Thanks for the review comments and suggestions.

Please find my response inline:

On 6/15/2020 10:15 AM, Anshuman Gupta wrote:
On 2020-06-08 at 15:31:03 +0530, Ankit Nautiyal wrote:
As per the current HDCP design, the driver selects the highest
version of HDCP that can be used to satisfy the content-protection
requirements of the user. Due to this, the content-protection
tests cannot test a lower version of HDCP, if the platform and the
display panel, both support higher HDCP version.

To provide some support for testing and debugging, a per-connector
debugfs is required to set the HDCP version via debugfs that the
kernel can consider, while enabling HDCP.

This patch adds a new debugfs entry for each connector that supports
HDCP. For enforcing a particular HDCP version for a connector, the user
can write into the debugfs for that connector.
IMHO this doesn't feel like a debugfs per connector, even if it is a
global singleton resource for all connectors, i don't see any problem in
that, may be a global debugfs would make sense here ?
The current solution was inline with the comments in the IGT patch, where the approach for a connector level debugfs was discussed by the community members. But I agree we don't necessarily require per connector debugfs for our use-case here. We can use a global resource for storing the request for HDCP version and use it if it is set, while enabling HDCP.
Perhaps will store it in dev_priv, instead of connector->hdcp.

I will try that out and send next version.

v2: As suggested by Jani Nikula:
-used kstrtouint_from_user() to directly read as uint from user buffer.
-used 32 bit flag instead of 64 bit for hdcp_ver flag.
-removed unnecessary prints and fixed other minor formatting issues.

Signed-off-by: Ankit Nautiyal <ankit.k.nauti...@intel.com>
---
  .../drm/i915/display/intel_display_debugfs.c  | 68 +++++++++++++++++++
  1 file changed, 68 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_display_debugfs.c 
b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
index 70525623bcdf..c01653d412e7 100644
--- a/drivers/gpu/drm/i915/display/intel_display_debugfs.c
+++ b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
@@ -2185,6 +2185,72 @@ static const struct file_operations 
i915_dsc_fec_support_fops = {
        .write = i915_dsc_fec_support_write
  };
+static int i915_hdcp_ver_request_show(struct seq_file *m, void *data)
+{
+       struct drm_connector *connector = m->private;
+       struct intel_connector *intel_connector = to_intel_connector(connector);
+       u32 hdcp_ver_flag;
+
+       if (connector->status != connector_status_connected)
+               return -ENODEV;
+
+       /* HDCP is supported by connector */
+       if (!intel_connector->hdcp.shim)
+               return -EINVAL;
+
+       hdcp_ver_flag = intel_connector->hdcp.debugfs_ver_request;
+       seq_printf(m, "HDCP_VER_FLAGS: %u\n", hdcp_ver_flag);
+
+       return 0;
+}
+
+static int i915_hdcp_ver_request_open(struct inode *inode,
+                                     struct file *file)
+{
+       return single_open(file, i915_hdcp_ver_request_show,
+                          inode->i_private);
+}
+
+static ssize_t i915_hdcp_ver_request_write(struct file *file,
+                                          const char __user *ubuf,
+                                          size_t len, loff_t *offp)
+{
+       unsigned int hdcp_ver = 0;
+       int ret;
+       struct drm_connector *connector =
+               ((struct seq_file *)file->private_data)->private;
+       struct intel_connector *intel_connector = to_intel_connector(connector);
+       struct intel_hdcp *hdcp = &intel_connector->hdcp;
+
+       if (!hdcp->shim)
+               return -EINVAL;
+
+       if (len == 0)
+               return 0;
+
+       ret = kstrtouint_from_user(ubuf, len, 0, &hdcp_ver);
+       if (ret < 0)
+               return ret;
+
+       if (hdcp_ver > HDCP_VERSION_MASK)
+               return -EINVAL;
+
+       hdcp->debugfs_ver_request = hdcp_ver;
A lockless assignment, this would probably not scale.
Could u please add some comment here for current IGT need this is ok,
but for any concurrent usgaes proper locking is required.
Thanks,
Anshuman

Agreed. I will add this as a note in comments in next version.

Thanks & Regards,
Ankit
+
+       *offp += len;
+
+       return len;
+}
+
+static const struct file_operations i915_hdcp_ver_request_fops = {
+       .owner = THIS_MODULE,
+       .open = i915_hdcp_ver_request_open,
+       .read = seq_read,
+       .llseek = seq_lseek,
+       .release = single_release,
+       .write = i915_hdcp_ver_request_write
+};
+
  /**
   * intel_connector_debugfs_add - add i915 specific connector debugfs files
   * @connector: pointer to a registered drm_connector
@@ -2215,6 +2281,8 @@ int intel_connector_debugfs_add(struct drm_connector 
*connector)
            connector->connector_type == DRM_MODE_CONNECTOR_HDMIB) {
                debugfs_create_file("i915_hdcp_sink_capability", S_IRUGO, root,
                                    connector, &i915_hdcp_sink_capability_fops);
+               debugfs_create_file("i915_hdcp_version_request", 0444, root,
+                                   connector, &i915_hdcp_ver_request_fops);
        }
if (INTEL_GEN(dev_priv) >= 10 &&
--
2.17.1


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