From: Chris Brandt Date: Tue, 14 Feb 2017 16:08:05 +0000 (-0500) Subject: clk: renesas: mstp: ensure register writes complete X-Git-Tag: v4.11-rc1~71^2 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=f59de563358eb9351b7f8f0ba2d3be2ebb70b93d;p=karo-tx-linux.git clk: renesas: mstp: ensure register writes complete When there is no status bit, it is possible for the clock enable/disable operation to have not completed by the time the driver code resumes execution. This is due to the fact that write operations are sometimes queued and delayed internally. Doing a read ensures the write operations has completed. Fixes: b6face404f38 ("ARM: shmobile: r7s72100: add essential clock nodes to dtsi") Signed-off-by: Chris Brandt Reviewed-by: Geert Uytterhoeven Signed-off-by: Stephen Boyd --- diff --git a/drivers/clk/renesas/clk-mstp.c b/drivers/clk/renesas/clk-mstp.c index 3ce819c26077..4067216bf31f 100644 --- a/drivers/clk/renesas/clk-mstp.c +++ b/drivers/clk/renesas/clk-mstp.c @@ -91,6 +91,12 @@ static int cpg_mstp_clock_endisable(struct clk_hw *hw, bool enable) value |= bitmask; cpg_mstp_write(group, value, group->smstpcr); + if (!group->mstpsr) { + /* dummy read to ensure write has completed */ + cpg_mstp_read(group, group->smstpcr); + barrier_data(group->smstpcr); + } + spin_unlock_irqrestore(&group->lock, flags); if (!enable || !group->mstpsr)