| Message ID | 20170228181214.6413-3-heiko@sntech.de (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
On 02/28, Heiko Stuebner wrote: > @@ -480,6 +481,19 @@ static void __init rk3036_clk_init(struct device_node *np) > > rockchip_register_restart_notifier(ctx, RK2928_GLB_SRST_FST, NULL); > > + clk = __clk_lookup("uart_pll_clk"); > + clk2 = __clk_lookup("gpll"); Can we do the register writes directly? Or call the appropriate function to twiddle some bits to change the parent before registering the clks? It's nice to avoid using clk API in provider drivers when we're getting clks from the provider itself, plus I'd like to get rid of __clk_lookup() one day. > + if (clk && clk2) { > + int ret = clk_set_parent(clk, clk2); > + > + if (ret < 0) > + pr_warn("%s: could not reparent uart_pll_clk to gpll\n", > + __func__); > + } else { > + pr_warn("%s: missing clocks to reparent uart_pll_clk to gpll\n", > + __func__); > + } > + > rockchip_clk_of_add_provider(np, ctx); > }
diff --git a/drivers/clk/rockchip/clk-rk3036.c b/drivers/clk/rockchip/clk-rk3036.c index dcde70f4c105..8b8d2c90c884 100644 --- a/drivers/clk/rockchip/clk-rk3036.c +++ b/drivers/clk/rockchip/clk-rk3036.c @@ -16,6 +16,7 @@ * GNU General Public License for more details. */ +#include <linux/clk.h> #include <linux/clk-provider.h> #include <linux/of.h> #include <linux/of_address.h> @@ -442,7 +443,7 @@ static void __init rk3036_clk_init(struct device_node *np) { struct rockchip_clk_provider *ctx; void __iomem *reg_base; - struct clk *clk; + struct clk *clk, *clk2; reg_base = of_iomap(np, 0); if (!reg_base) { @@ -480,6 +481,19 @@ static void __init rk3036_clk_init(struct device_node *np) rockchip_register_restart_notifier(ctx, RK2928_GLB_SRST_FST, NULL); + clk = __clk_lookup("uart_pll_clk"); + clk2 = __clk_lookup("gpll"); + if (clk && clk2) { + int ret = clk_set_parent(clk, clk2); + + if (ret < 0) + pr_warn("%s: could not reparent uart_pll_clk to gpll\n", + __func__); + } else { + pr_warn("%s: missing clocks to reparent uart_pll_clk to gpll\n", + __func__); + } + rockchip_clk_of_add_provider(np, ctx); } CLK_OF_DECLARE(rk3036_cru, "rockchip,rk3036-cru", rk3036_clk_init);
The shared uart-pll is on boot a child of the apll that can get changed by cpu frequency scaling. So move it away to the more stable gpll to make sure the uart doesn't break on cpu frequency changes. This turned up during the 4.11 merge-window when commit 6a171b299379 ("serial: 8250_dw: Allow hardware flow control to be used") added general termios enablement making the uart on rk3036 change frequency and thus making it susceptible for the frequency scaling issue. Signed-off-by: Heiko Stuebner <heiko@sntech.de> --- drivers/clk/rockchip/clk-rk3036.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-)