From da321133b53caf7889ed3ca1dabe4cc368db2604 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Uwe=20Kleine-K=C3=B6nig?= Date: Sat, 21 Feb 2015 11:40:23 +0100 Subject: [PATCH] clk: divider: fix calculation of maximal parent rate for a given divider MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit The rate provided at the output of a clk-divider is calculated as: DIV_ROUND_UP(parent_rate, div) since commit b11d282dbea2 (clk: divider: fix rate calculation for fractional rates). So to yield a rate not bigger than r parent_rate must be <= r * div. The effect of choosing a parent rate that is too big as was done before this patch results in wrongly ruling out good dividers. Note that this is not a complete fix as __clk_round_rate might return a value >= its 2nd parameter. Also for dividers with CLK_DIVIDER_ROUND_CLOSEST set the calculation is not accurate. But this fixes the test case by Sascha Hauer that uses a chain of three dividers under a fixed clock. Fixes: b11d282dbea2 (clk: divider: fix rate calculation for fractional rates) Suggested-by: Sascha Hauer Signed-off-by: Uwe Kleine-König Acked-by: Sascha Hauer Signed-off-by: Michael Turquette --- Reading git-format-patch failed