diff options
| author |   David Ung <davidu@nvidia.com> | 2014-12-05 15:30:05 -0800 |
|---|---|---|
| committer |   Thierry Reding <treding@nvidia.com> | 2015-01-27 10:14:40 +0100 |
| commit | 2dafd63682d0e2be20b913f370d9f29eb0d483f7 (patch) | |
| tree | f817efde1e0c4d2ef2c1b2526db242e1963bd534 /drivers/gpu/drm/tegra/mipi-phy.c | |
| parent | drm/tegra: dsi: Reset across ->exit()/->init() (diff) | |
| download | linux-dev-2dafd63682d0e2be20b913f370d9f29eb0d483f7.tar.xz linux-dev-2dafd63682d0e2be20b913f370d9f29eb0d483f7.zip | |
drm/tegra: dsi: Adjust D-PHY timing
Compliance testing shows that HS Trail is off by -12%. Increase the HS
Trail time to make this test pass.
Signed-off-by: David Ung <davidu@nvidia.com>
[treding@nvidia.com: update specification references, add comment]
Signed-off-by: Thierry Reding <treding@nvidia.com>
Diffstat (limited to 'drivers/gpu/drm/tegra/mipi-phy.c')
| -rw-r--r-- | drivers/gpu/drm/tegra/mipi-phy.c | 25 |
1 files changed, 19 insertions, 6 deletions
diff --git a/drivers/gpu/drm/tegra/mipi-phy.c b/drivers/gpu/drm/tegra/mipi-phy.c index 486d19d589c8..ba2ae6511957 100644 --- a/drivers/gpu/drm/tegra/mipi-phy.c +++ b/drivers/gpu/drm/tegra/mipi-phy.c @@ -12,9 +12,9 @@ #include "mipi-phy.h" /* - * Default D-PHY timings based on MIPI D-PHY specification. Derived from - * the valid ranges specified in Section 5.9 of the D-PHY specification - * with minor adjustments. + * Default D-PHY timings based on MIPI D-PHY specification. Derived from the + * valid ranges specified in Section 6.9, Table 14, Page 40 of the D-PHY + * specification (v1.2) with minor adjustments. */ int mipi_dphy_timing_get_default(struct mipi_dphy_timing *timing, unsigned long period) @@ -34,7 +34,20 @@ int mipi_dphy_timing_get_default(struct mipi_dphy_timing *timing, timing->hszero = 145 + 5 * period; timing->hssettle = 85 + 6 * period; timing->hsskip = 40; - timing->hstrail = max(8 * period, 60 + 4 * period); + + /* + * The MIPI D-PHY specification (Section 6.9, v1.2, Table 14, Page 40) + * contains this formula as: + * + * T_HS-TRAIL = max(n * 8 * period, 60 + n * 4 * period) + * + * where n = 1 for forward-direction HS mode and n = 4 for reverse- + * direction HS mode. There's only one setting and this function does + * not parameterize on anything other that period, so this code will + * assumes that reverse-direction HS mode is supported and uses n = 4. + */ + timing->hstrail = max(4 * 8 * period, 60 + 4 * 4 * period); + timing->init = 100000; timing->lpx = 60; timing->taget = 5 * timing->lpx; @@ -46,8 +59,8 @@ int mipi_dphy_timing_get_default(struct mipi_dphy_timing *timing, } /* - * Validate D-PHY timing according to MIPI Alliance Specification for D-PHY, - * Section 5.9 "Global Operation Timing Parameters". + * Validate D-PHY timing according to MIPI D-PHY specification (v1.2, Section + * Section 6.9 "Global Operation Timing Parameters"). */ int mipi_dphy_timing_validate(struct mipi_dphy_timing *timing, unsigned long period) |