Fixes/improvement in snps-phy HDMI PLL algorithm.
Ankit Nautiyal (2): drm/i915/snps_hdmi_pll: Fix 64-bit divisor truncation by using div64_u64 drm/i915/snps_hdmi_pll: Use clamp() instead of max(min())
drivers/gpu/drm/i915/display/intel_snps_hdmi_pll.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
DIV_ROUND_CLOSEST_ULL uses do_div(), which expects a 32-bit divisor. When passing a 64-bit constant like CURVE2_MULTIPLIER, the value is silently truncated to u32, potentially leading to incorrect results on large divisors.
Replace DIV_ROUND_CLOSEST_ULL with DIV64_U64_ROUND_CLOSEST which correctly handles full 64-bit division.
v2: Use DIV64_U64_ROUND_CLOSEST instead of div64_u64 macro. (Jani)
Fixes: 5947642004bf ("drm/i915/display: Add support for SNPS PHY HDMI PLL algorithm for DG2") Reported-by: Vas Novikov vasya.novikov@gmail.com Closes: https://lore.kernel.org/all/8d7c7958-9558-4c8a-a81a-e9310f2d8852@gmail.com/ Cc: Ankit Nautiyal ankit.k.nautiyal@intel.com Cc: Suraj Kandpal suraj.kandpal@intel.com Cc: Jani Nikula jani.nikula@intel.com Cc: Vas Novikov vasya.novikov@gmail.com Cc: stable@vger.kernel.org # v6.15+ Signed-off-by: Ankit Nautiyal ankit.k.nautiyal@intel.com --- drivers/gpu/drm/i915/display/intel_snps_hdmi_pll.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_snps_hdmi_pll.c b/drivers/gpu/drm/i915/display/intel_snps_hdmi_pll.c index 74bb3bedf30f..5111bdc3075b 100644 --- a/drivers/gpu/drm/i915/display/intel_snps_hdmi_pll.c +++ b/drivers/gpu/drm/i915/display/intel_snps_hdmi_pll.c @@ -103,8 +103,8 @@ static void get_ana_cp_int_prop(u64 vco_clk, DIV_ROUND_DOWN_ULL(curve_1_interpolated, CURVE0_MULTIPLIER)));
ana_cp_int_temp = - DIV_ROUND_CLOSEST_ULL(DIV_ROUND_DOWN_ULL(adjusted_vco_clk1, curve_2_scaled1), - CURVE2_MULTIPLIER); + DIV64_U64_ROUND_CLOSEST(DIV_ROUND_DOWN_ULL(adjusted_vco_clk1, curve_2_scaled1), + CURVE2_MULTIPLIER);
*ana_cp_int = max(1, min(ana_cp_int_temp, 127));
The values of ana_cp_int, and ana_cp_prop are clamped between 1 and 127. Use the more intuitive and readable clamp() macro instead of using nested max(min(...)).
Signed-off-by: Ankit Nautiyal ankit.k.nautiyal@intel.com --- drivers/gpu/drm/i915/display/intel_snps_hdmi_pll.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_snps_hdmi_pll.c b/drivers/gpu/drm/i915/display/intel_snps_hdmi_pll.c index 5111bdc3075b..7fe6b4a18213 100644 --- a/drivers/gpu/drm/i915/display/intel_snps_hdmi_pll.c +++ b/drivers/gpu/drm/i915/display/intel_snps_hdmi_pll.c @@ -106,7 +106,7 @@ static void get_ana_cp_int_prop(u64 vco_clk, DIV64_U64_ROUND_CLOSEST(DIV_ROUND_DOWN_ULL(adjusted_vco_clk1, curve_2_scaled1), CURVE2_MULTIPLIER);
- *ana_cp_int = max(1, min(ana_cp_int_temp, 127)); + *ana_cp_int = clamp(ana_cp_int_temp, 1, 127);
curve_2_scaled_int = curve_2_scaled1 * (*ana_cp_int);
@@ -125,7 +125,7 @@ static void get_ana_cp_int_prop(u64 vco_clk, curve_1_interpolated);
*ana_cp_prop = DIV64_U64_ROUND_UP(adjusted_vco_clk2, curve_2_scaled2); - *ana_cp_prop = max(1, min(*ana_cp_prop, 127)); + *ana_cp_prop = clamp(*ana_cp_prop, 1, 127); }
static void compute_hdmi_tmds_pll(u64 pixel_clock, u32 refclk,
Hi,
Thanks for your patch.
FYI: kernel test robot notices the stable kernel rule is not satisfied.
The check is based on https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html#opti...
Rule: add the tag "Cc: stable@vger.kernel.org" in the sign-off area to have the patch automatically included in the stable tree. Subject: [PATCH 2/2] drm/i915/snps_hdmi_pll: Use clamp() instead of max(min()) Link: https://lore.kernel.org/stable/20250618130951.1596587-3-ankit.k.nautiyal%40i...
On Wed, 18 Jun 2025, Ankit Nautiyal ankit.k.nautiyal@intel.com wrote:
Fixes/improvement in snps-phy HDMI PLL algorithm.
Reviewed-by: Jani Nikula jani.nikula@intel.com
Ankit Nautiyal (2): drm/i915/snps_hdmi_pll: Fix 64-bit divisor truncation by using div64_u64 drm/i915/snps_hdmi_pll: Use clamp() instead of max(min())
drivers/gpu/drm/i915/display/intel_snps_hdmi_pll.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
On 6/19/2025 1:21 AM, Jani Nikula wrote:
On Wed, 18 Jun 2025, Ankit Nautiyal ankit.k.nautiyal@intel.com wrote:
Fixes/improvement in snps-phy HDMI PLL algorithm.
Reviewed-by: Jani Nikula jani.nikula@intel.com
Thank you once again, Jani, for pointing out the sparse warning and for your reviews.
The series has been pushed to drm-intel-next.
Regards,
Ankit
Ankit Nautiyal (2): drm/i915/snps_hdmi_pll: Fix 64-bit divisor truncation by using div64_u64 drm/i915/snps_hdmi_pll: Use clamp() instead of max(min())
drivers/gpu/drm/i915/display/intel_snps_hdmi_pll.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
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