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To: Jorge Ramirez <jorge.ramirez-ortiz@linaro.org>,
 "Guodong Xu" <guodong.xu@linaro.org>, sboyd@codeaurora.org,
 xinliang.liu@linaro.org, john.stultz@linaro.org
From: Michael Turquette <mturquette@baylibre.com>
In-Reply-To: <577E18E9.5060308@linaro.org>
Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
 linux-clk@vger.kernel.org
References: <1467189955-21694-1-git-send-email-guodong.xu@linaro.org>
 <1467189955-21694-2-git-send-email-guodong.xu@linaro.org>
 <146784139106.73491.6417383579004254897@resonance>
 <577DF73A.1030701@linaro.org> <577E18E9.5060308@linaro.org>
Message-ID: <146794250343.73491.5529591541364046694@resonance>
Subject: Re: [PATCH v2 2/2] clk: hi6220: initialize UART1 clock to 150MHz
Date: Thu, 07 Jul 2016 18:48:23 -0700
List-ID: <linux-clk.vger.kernel.org>

Quoting Jorge Ramirez (2016-07-07 01:55:05)
> On 07/07/2016 08:31 AM, Jorge Ramirez wrote:
> > On 07/06/2016 11:43 PM, Michael Turquette wrote:
> >> Quoting Guodong Xu (2016-06-29 01:45:55)
> >>> >From: Jorge Ramirez-Ortiz<jorge.ramirez-ortiz@linaro.org>
> >>> >
> >>> >Early at boot, during the sys_clk initialization, make sure UART1 us=
es
> >>> >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<jorge.ramirez-ortiz@linaro.org>
> >>> >Signed-off-by: Guodong Xu<guodong.xu@linaro.org>
> >>> >---
> >>> >  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).
> >
> >
> I have v3 ready (changes done in amba-pl011.c and devicetree/bindings)
> please let me know if I should send those instead.

Yes, please do. Are you using the clock-assigned-rates property?

Regards,
Mike

> =

> =

>=20