This is a note to let you know that I've just added the patch titled clk: at91: clk-main: update key before writing AT91_CKGR_MOR to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: clk-at91-clk-main-update-key-before-writing-at91_ckg.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 8c415c0bd377f4f18aa7f8496107acc276cb15e4 Author: Claudiu Beznea <claudiu.beznea@xxxxxxxxxxxxx> Date: Tue Aug 25 09:59:10 2020 +0300 clk: at91: clk-main: update key before writing AT91_CKGR_MOR [ Upstream commit 85d071e7f19a6a9abf30476b90b3819642568756 ] SAMA5D2 datasheet specifies on chapter 33.22.8 (PMC Clock Generator Main Oscillator Register) that writing any value other than 0x37 on KEY field aborts the write operation. Use the key when selecting main clock parent. Fixes: 27cb1c2083373 ("clk: at91: rework main clk implementation") Signed-off-by: Claudiu Beznea <claudiu.beznea@xxxxxxxxxxxxx> Reviewed-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx> Link: https://lore.kernel.org/r/1598338751-20607-3-git-send-email-claudiu.beznea@xxxxxxxxxxxxx Signed-off-by: Stephen Boyd <sboyd@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/clk/at91/clk-main.c b/drivers/clk/at91/clk-main.c index 90988e7a5b47f..2e7da9b379d48 100644 --- a/drivers/clk/at91/clk-main.c +++ b/drivers/clk/at91/clk-main.c @@ -517,12 +517,17 @@ static int clk_sam9x5_main_set_parent(struct clk_hw *hw, u8 index) return -EINVAL; regmap_read(regmap, AT91_CKGR_MOR, &tmp); - tmp &= ~MOR_KEY_MASK; if (index && !(tmp & AT91_PMC_MOSCSEL)) - regmap_write(regmap, AT91_CKGR_MOR, tmp | AT91_PMC_MOSCSEL); + tmp = AT91_PMC_MOSCSEL; else if (!index && (tmp & AT91_PMC_MOSCSEL)) - regmap_write(regmap, AT91_CKGR_MOR, tmp & ~AT91_PMC_MOSCSEL); + tmp = 0; + else + return 0; + + regmap_update_bits(regmap, AT91_CKGR_MOR, + AT91_PMC_MOSCSEL | MOR_KEY_MASK, + tmp | AT91_PMC_KEY); while (!clk_sam9x5_main_ready(regmap)) cpu_relax();