According to Bspec clock divisor registers in GeminiLake should be initialized by shifting 1(<<) to amount of correspondent divisor. While i915 was writing all this time that value as is.

Surprisingly that it by accident worked, until we met some issues with Microtech Etab.

v2: Added Fixes tag and cc v3: Added stable to cc as well.

Signed-off-by: stanislav.lisovskiy@intel.com Reviewed-by: Vandita Kulkarni vandita.kulkarni@intel.com Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=108826 Fixes: bcc657004841 ("drm/i915/glk: Program txesc clock divider for GLK") Cc: Deepak M m.deepak@intel.com Cc: Madhav Chauhan madhav.chauhan@intel.com Cc: Jani Nikula jani.nikula@intel.com 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 --- drivers/gpu/drm/i915/display/vlv_dsi_pll.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/vlv_dsi_pll.c b/drivers/gpu/drm/i915/display/vlv_dsi_pll.c index 99cc3e2e9c2c..f016a776a39e 100644 --- a/drivers/gpu/drm/i915/display/vlv_dsi_pll.c +++ b/drivers/gpu/drm/i915/display/vlv_dsi_pll.c @@ -396,8 +396,8 @@ static void glk_dsi_program_esc_clock(struct drm_device *dev, else txesc2_div = 10;

- I915_WRITE(MIPIO_TXESC_CLK_DIV1, txesc1_div & GLK_TX_ESC_CLK_DIV1_MASK); - I915_WRITE(MIPIO_TXESC_CLK_DIV2, txesc2_div & GLK_TX_ESC_CLK_DIV2_MASK); + I915_WRITE(MIPIO_TXESC_CLK_DIV1, (1 << (txesc1_div - 1)) & GLK_TX_ESC_CLK_DIV1_MASK); + I915_WRITE(MIPIO_TXESC_CLK_DIV2, (1 << (txesc2_div - 1)) & GLK_TX_ESC_CLK_DIV2_MASK); }

/* Program BXT Mipi clocks and dividers */