linux-kernel - [PATCH 5.2 125/144] drm/i915: Fix wrong escape clock divisor init for GLK

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Date:   Wed, 14 Aug 2019 19:01:21 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Stanislav Lisovskiy <stanislav.lisovskiy@...el.com>,
        Vandita Kulkarni <vandita.kulkarni@...el.com>,
        Deepak M <m.deepak@...el.com>,
        Madhav Chauhan <madhav.chauhan@...el.com>,
        Jani Nikula <jani.nikula@...el.com>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        intel-gfx@...ts.freedesktop.org
Subject: [PATCH 5.2 125/144] drm/i915: Fix wrong escape clock divisor init for GLK

From: Stanislav Lisovskiy <stanislav.lisovskiy@...el.com>

commit 73a0ff0b30af79bf0303d557eb82f1d1945bb6ee upstream.

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 <stanislav.lisovskiy@...el.com>
Reviewed-by: Vandita Kulkarni <vandita.kulkarni@...el.com>
Bugzilla: 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@...el.com>
Cc: Madhav Chauhan <madhav.chauhan@...el.com>
Cc: Jani Nikula <jani.nikula@...el.com>
Cc: Jani Nikula <jani.nikula@...ux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@...el.com>
Cc: intel-gfx@...ts.freedesktop.org
Cc: stable@...r.kernel.org
Signed-off-by: Jani Nikula <jani.nikula@...el.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190712081938.14185-1-stanislav.lisovskiy@intel.com
(cherry picked from commit ce52ad5dd52cfaf3398058384e0ff94134bbd89c)
Signed-off-by: Jani Nikula <jani.nikula@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/gpu/drm/i915/vlv_dsi_pll.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/gpu/drm/i915/vlv_dsi_pll.c
+++ b/drivers/gpu/drm/i915/vlv_dsi_pll.c
@@ -394,8 +394,8 @@ static void glk_dsi_program_esc_clock(st
 	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 */