On 2019-12-12 at 14:02:19 -0500, Sean Paul wrote:

From: Sean Paul seanpaul@chromium.org

This patch fixes a few bugs:

1- We weren't taking into account sha_leftovers when adding multiple ksvs to sha_text. As such, we were or'ing the end of ksv[j - 1] with the beginning of ksv[j]

2- In the sha_leftovers == 2 and sha_leftovers == 3 case, bstatus was being placed on the wrong half of sha_text, overlapping the leftover ksv value

3- In the sha_leftovers == 2 case, we need to manually terminate the byte stream with 0x80 since the hardware doesn't have enough room to add it after writing M0

The upside is that all of the "HDCP supported" HDMI repeaters I could find on Amazon just strip HDCP anyways, so it turns out to be _really_ hard to hit any of these cases without an MST hub, which is not (yet) supported. Oh, and the sha_leftovers == 1 case works perfectly!

Yes. The repeaters tested at our side too with sha_leftovers = 1 with mostly ksv count of 1. non availability of the repeaters is killer here.

Fixes: ee5e5e7a5e0f ("drm/i915: Add HDCP framework + base implementation") Cc: Chris Wilson chris@chris-wilson.co.uk Cc: Ramalingam C ramalingam.c@intel.com Cc: Daniel Vetter daniel.vetter@ffwll.ch Cc: Sean Paul seanpaul@chromium.org Cc: Jani Nikula jani.nikula@linux.intel.com Cc: Joonas Lahtinen joonas.lahtinen@linux.intel.com Cc: Rodrigo Vivi rodrigo.vivi@intel.com Cc: intel-gfx@lists.freedesktop.org Cc: stable@vger.kernel.org # v4.17+ Signed-off-by: Sean Paul seanpaul@chromium.org Link: https://patchwork.freedesktop.org/patch/msgid/20191203173638.94919-2-sean@po... #v1

Changes in v2:

-None

drivers/gpu/drm/i915/display/intel_hdcp.c | 25 +++++++++++++++++------ include/drm/drm_hdcp.h | 3 +++ 2 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_hdcp.c b/drivers/gpu/drm/i915/display/intel_hdcp.c index 0fdbd39f6641..eaab9008feef 100644 --- a/drivers/gpu/drm/i915/display/intel_hdcp.c +++ b/drivers/gpu/drm/i915/display/intel_hdcp.c @@ -335,8 +335,10 @@ int intel_hdcp_validate_v_prime(struct intel_connector *connector, /* Fill up the empty slots in sha_text and write it out */ sha_empty = sizeof(sha_text) - sha_leftovers;

• for (j = 0; j < sha_empty; j++)
  

• 	sha_text |= ksv[j] << ((sizeof(sha_text) - j - 1) * 8);
  

• for (j = 0; j < sha_empty; j++) {
  

• 	u8 off = ((sizeof(sha_text) - j - 1 - sha_leftovers) * 8);
  

Didn't hit this as ksv count was 1 mostly with sha_leftovers = 1. Thanks for fixing it.

• 	sha_text |= ksv[j] << off;
  

• }
  

ret = intel_write_sha_text(dev_priv, sha_text); if (ret < 0) @@ -426,7 +428,7 @@ int intel_hdcp_validate_v_prime(struct intel_connector *connector, } else if (sha_leftovers == 2) { /* Write 32 bits of text */ I915_WRITE(HDCP_REP_CTL, rep_ctl | HDCP_SHA1_TEXT_32);

• sha_text |= bstatus[0] << 24 | bstatus[1] << 16;
  

• sha_text |= bstatus[0] << 8 | bstatus[1];
  

  ret = intel_write_sha_text(dev_priv, sha_text); if (ret < 0) return ret;

@@ -440,16 +442,27 @@ int intel_hdcp_validate_v_prime(struct intel_connector *connector, return ret; sha_idx += sizeof(sha_text); }

• /*
  

•  * Terminate the SHA-1 stream by hand. For the other leftover
  

•  * cases this is appended by the hardware.
  

•  */
  

• I915_WRITE(HDCP_REP_CTL, rep_ctl | HDCP_SHA1_TEXT_32);
  

• sha_text = DRM_HDCP_SHA1_TERMINATOR << 24;
  

• ret = intel_write_sha_text(dev_priv, sha_text);
  

• if (ret < 0)
  

• 	return ret;
  

• sha_idx += sizeof(sha_text);
  

  } else if (sha_leftovers == 3) {

• /* Write 32 bits of text */
  

• /* Write 32 bits of text (filled from LSB) */
  

  I915_WRITE(HDCP_REP_CTL, rep_ctl | HDCP_SHA1_TEXT_32);

• sha_text |= bstatus[0] << 24;
  

• sha_text |= bstatus[0];
  

Looks good to me though this path never been exercised. Hopefully MST will do it.

Reviewed-by: Ramalingam C ramalingam.c@intel.com

ret = intel_write_sha_text(dev_priv, sha_text);
if (ret < 0)
	return ret;
sha_idx += sizeof(sha_text);

• /* Write 8 bits of text, 24 bits of M0 */
  

• /* Write 8 bits of text (filled from LSB), 24 bits of M0 */
  

  I915_WRITE(HDCP_REP_CTL, rep_ctl | HDCP_SHA1_TEXT_8); ret = intel_write_sha_text(dev_priv, bstatus[1]); if (ret < 0)

diff --git a/include/drm/drm_hdcp.h b/include/drm/drm_hdcp.h index 06a11202a097..20498c822204 100644 --- a/include/drm/drm_hdcp.h +++ b/include/drm/drm_hdcp.h @@ -29,6 +29,9 @@ /* Slave address for the HDCP registers in the receiver */ #define DRM_HDCP_DDC_ADDR 0x3A +/* Value to use at the end of the SHA-1 bytestream used for repeaters */ +#define DRM_HDCP_SHA1_TERMINATOR 0x80

/* HDCP register offsets for HDMI/DVI devices */ #define DRM_HDCP_DDC_BKSV 0x00

#define DRM_HDCP_DDC_RI_PRIME 0x08

Sean Paul, Software Engineer, Google / Chromium OS