[PATCH v2 2/2] clk: hi6220: initialize UART1 clock to 150MHz

On 07/06/2016 11:43 PM, Michael Turquette wrote:

Quoting Guodong Xu (2016-06-29 01:45:55)

quoted

quoted

From: Jorge Ramirez-Ortiz<redacted>

Early at boot, during the sys_clk initialization, make sure UART1 uses
the higher frequency clock, 150MHz.

This enables support for higher baud rates (up to 3Mbps) in UART1, which
is required by faster bluetooth transfers.

v2: use clk_set_rate() to propergate clock settings.

Signed-off-by: Jorge Ramirez-Ortiz<redacted>
Signed-off-by: Guodong Xu<redacted>
---
 drivers/clk/hisilicon/clk-hi6220.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/clk/hisilicon/clk-hi6220.c b/drivers/clk/hisilicon/clk-hi6220.c
index a36ffcb..631c56f 100644
--- a/drivers/clk/hisilicon/clk-hi6220.c
+++ b/drivers/clk/hisilicon/clk-hi6220.c

@@ -12,6 +12,7 @@
 
 #include <linux/kernel.h>
 #include <linux/clk-provider.h>
+#include <linux/clk.h>
 #include <linux/clkdev.h>
 #include <linux/io.h>
 #include <linux/of.h>

@@ -192,6 +193,9 @@ static void __init hi6220_clk_sys_init(struct device_node *np)
 
        hi6220_clk_register_divider(hi6220_div_clks_sys,
                        ARRAY_SIZE(hi6220_div_clks_sys), clk_data);
+
+       if (clk_set_rate(clk_data->clk_data.clks[HI6220_UART1_SRC], 150000000))
+               pr_err("failed to set uart1 clock rate\n");

Why doesn't the UART driver call clk_get and then clk_set_rate on this
clock? Why do it in the clk provider driver?

yes that was my initial choice as well; in the end I opted to do it in 
the clock driver because of it being a value that will not have to ever 
change for the SoC and - maybe more importantly- because of not having a 
DT property available for the primecell pl011 uart where to  specify the 
value (so I thought this was a less intrusive implementation).