diff options
| author | Ville Syrjälä <ville.syrjala@linux.intel.com> | 2022-09-07 12:10:56 +0300 |
|---|---|---|
| committer | Ville Syrjälä <ville.syrjala@linux.intel.com> | 2022-09-08 14:23:28 +0300 |
| commit | c46af5621adc766cf1a7cac300d577a39849862f (patch) | |
| tree | d54d26f4d0fd94f405ae09100bc85877d1644e64 /drivers/gpu/drm/i915/display/intel_display.c | |
| parent | e6f29923c0489b6fec1ac000f2c045df43ec081c (diff) | |
drm/i915: Use a fixed N value always
Windows/BIOS always uses fixed N values. Let's match that
behaviour.
Allows us to also get rid of that constant_n quirk stuff.
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220907091057.11572-17-ville.syrjala@linux.intel.com
Diffstat (limited to 'drivers/gpu/drm/i915/display/intel_display.c')
| -rw-r--r-- | drivers/gpu/drm/i915/display/intel_display.c | 38 |
1 files changed, 18 insertions, 20 deletions
diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c index e7c28ff8b0e2..c57b5b1d6940 100644 --- a/drivers/gpu/drm/i915/display/intel_display.c +++ b/drivers/gpu/drm/i915/display/intel_display.c @@ -2721,19 +2721,11 @@ intel_reduce_m_n_ratio(u32 *num, u32 *den) } } -static void compute_m_n(unsigned int m, unsigned int n, - u32 *ret_m, u32 *ret_n, - bool constant_n) +static void compute_m_n(u32 *ret_m, u32 *ret_n, + u32 m, u32 n, u32 constant_n) { - /* - * Several DP dongles in particular seem to be fussy about - * too large link M/N values. Give N value as 0x8000 that - * should be acceptable by specific devices. 0x8000 is the - * specified fixed N value for asynchronous clock mode, - * which the devices expect also in synchronous clock mode. - */ if (constant_n) - *ret_n = DP_LINK_CONSTANT_N_VALUE; + *ret_n = constant_n; else *ret_n = min_t(unsigned int, roundup_pow_of_two(n), DATA_LINK_N_MAX); @@ -2745,22 +2737,28 @@ void intel_link_compute_m_n(u16 bits_per_pixel, int nlanes, int pixel_clock, int link_clock, struct intel_link_m_n *m_n, - bool constant_n, bool fec_enable) + bool fec_enable) { u32 data_clock = bits_per_pixel * pixel_clock; if (fec_enable) data_clock = intel_dp_mode_to_fec_clock(data_clock); + /* + * Windows/BIOS uses fixed M/N values always. Follow suit. + * + * Also several DP dongles in particular seem to be fussy + * about too large link M/N values. Presumably the 20bit + * value used by Windows/BIOS is acceptable to everyone. + */ m_n->tu = 64; - compute_m_n(data_clock, - link_clock * nlanes * 8, - &m_n->data_m, &m_n->data_n, - constant_n); - - compute_m_n(pixel_clock, link_clock, - &m_n->link_m, &m_n->link_n, - constant_n); + compute_m_n(&m_n->data_m, &m_n->data_n, + data_clock, link_clock * nlanes * 8, + 0x8000000); + + compute_m_n(&m_n->link_m, &m_n->link_n, + pixel_clock, link_clock, + 0x80000); } static void intel_panel_sanitize_ssc(struct drm_i915_private *dev_priv) |