From: "Anson.Huang-KZfg59tc24xl57MIdRCFDg@public.gmane.org" <Anson.Huang-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
To: Fabio Estevam <festevam-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: Shawn Guo <Shawn.Guo-KZfg59tc24xl57MIdRCFDg@public.gmane.org>,
Sascha Hauer <kernel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>,
"devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
"linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org"
<linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org>
Subject: Re: [PATCH 0/3] move gpt per clk parent for ipg_per to OSC
Date: Thu, 4 Sep 2014 23:37:21 +0000 [thread overview]
Message-ID: <9B0C19C6-6C3B-47DC-9DC4-5BD42CE294A4@freescale.com> (raw)
In-Reply-To: <CAOMZO5BOfsvrH3ijxKwyGemEW-B60n-+4wpDZ5xfC98efM469w-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset="gb2312", Size: 1853 bytes --]
Hi, Fabio
can I know why you want to run the new kernel with old dtb?
Sent from Anson's iPhone
> ÔÚ 2014Äê9ÔÂ5ÈÕ£¬6:50£¬"Fabio Estevam" <festevam@gmail.com> дµÀ£º
>
>> On Wed, Sep 3, 2014 at 4:36 AM, Anson Huang <b20788@freescale.com> wrote:
>> Currently, gpt timer's clock is from ipg_per, and ipg_per clock is from ipg
>> on most of i.MX6 series SOCs, but ipg's rate may be scaled when system enters
>> low bus mode for saving power, then gpt timer's clock rate will be scaled as
>> well, as system timer should be kept stable and NOT drift, better to keep gpt
>> timer's clk at fixed rate, on i.MX6Q TO > 1.0, i.MX6DL and i.MX6SX, there is
>> OSC clk available for gpt timer, we should enable this feature, the hardware
>> design is as below:
>>
>> i.MX6Q TO > 1.0: GPT_CR_CLKSRC, 3b'101 selects fix clock
>> of OSC / 8 for gpt per clk;
>> i.MX6DL and i.MX6SX: GPT_CR_CLKSRC, 3b'101 selects OSC
>> for gpt per clk, and we must enable GPT_CR_24MEM to
>> enable OSC clk source for gpt per, GPT_PR_PRESCALER24M
>> is for pre-scaling of this OSC clk, here set it to 8
>> to make gpt per clk is 3MHz;
>> i.MX6SL: ipg_per can be from OSC directly, so no need to
>> implement this new clk source for gpt per.
>>
>> Anson Huang (3):
>> ARM: imx: add gpt_3m clk for i.mx6qdl
>> ARM: dts: imx6: change gpt per clk to gpt_3m on i.mx6qdl and i.mx6sx
>> ARM: imx: source gpt per clk from OSC for system timer
>
> This patch series works fine if we use the new dtb and new kernel.
>
> However, booting a kernel with these series applied and using an old
> dtb we get a system with broken timer.
>
> 'sleep 1' takes something like 20 seconds in this case.
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WARNING: multiple messages have this Message-ID (diff)
From: Anson.Huang@freescale.com (Anson.Huang at freescale.com)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 0/3] move gpt per clk parent for ipg_per to OSC
Date: Thu, 4 Sep 2014 23:37:21 +0000 [thread overview]
Message-ID: <9B0C19C6-6C3B-47DC-9DC4-5BD42CE294A4@freescale.com> (raw)
In-Reply-To: <CAOMZO5BOfsvrH3ijxKwyGemEW-B60n-+4wpDZ5xfC98efM469w@mail.gmail.com>
Hi, Fabio
can I know why you want to run the new kernel with old dtb?
Sent from Anson's iPhone
> ? 2014?9?5??6:50?"Fabio Estevam" <festevam@gmail.com> ???
>
>> On Wed, Sep 3, 2014 at 4:36 AM, Anson Huang <b20788@freescale.com> wrote:
>> Currently, gpt timer's clock is from ipg_per, and ipg_per clock is from ipg
>> on most of i.MX6 series SOCs, but ipg's rate may be scaled when system enters
>> low bus mode for saving power, then gpt timer's clock rate will be scaled as
>> well, as system timer should be kept stable and NOT drift, better to keep gpt
>> timer's clk at fixed rate, on i.MX6Q TO > 1.0, i.MX6DL and i.MX6SX, there is
>> OSC clk available for gpt timer, we should enable this feature, the hardware
>> design is as below:
>>
>> i.MX6Q TO > 1.0: GPT_CR_CLKSRC, 3b'101 selects fix clock
>> of OSC / 8 for gpt per clk;
>> i.MX6DL and i.MX6SX: GPT_CR_CLKSRC, 3b'101 selects OSC
>> for gpt per clk, and we must enable GPT_CR_24MEM to
>> enable OSC clk source for gpt per, GPT_PR_PRESCALER24M
>> is for pre-scaling of this OSC clk, here set it to 8
>> to make gpt per clk is 3MHz;
>> i.MX6SL: ipg_per can be from OSC directly, so no need to
>> implement this new clk source for gpt per.
>>
>> Anson Huang (3):
>> ARM: imx: add gpt_3m clk for i.mx6qdl
>> ARM: dts: imx6: change gpt per clk to gpt_3m on i.mx6qdl and i.mx6sx
>> ARM: imx: source gpt per clk from OSC for system timer
>
> This patch series works fine if we use the new dtb and new kernel.
>
> However, booting a kernel with these series applied and using an old
> dtb we get a system with broken timer.
>
> 'sleep 1' takes something like 20 seconds in this case.
next prev parent reply other threads:[~2014-09-04 23:37 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-03 7:36 [PATCH 0/3] move gpt per clk parent for ipg_per to OSC Anson Huang
2014-09-03 7:36 ` Anson Huang
2014-09-03 7:36 ` [PATCH 3/3] ARM: imx: source gpt per clk from OSC for system timer Anson Huang
2014-09-03 7:36 ` Anson Huang
[not found] ` <1409729805-9741-1-git-send-email-b20788-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
2014-09-03 7:36 ` [PATCH 1/3] ARM: imx: add gpt_3m clk for i.mx6qdl Anson Huang
2014-09-03 7:36 ` Anson Huang
2014-09-03 7:36 ` [PATCH 2/3] ARM: dts: imx6: change gpt per clk to gpt_3m on i.mx6qdl and i.mx6sx Anson Huang
2014-09-03 7:36 ` Anson Huang
2014-09-04 3:56 ` [PATCH 0/3] move gpt per clk parent for ipg_per to OSC Shawn Guo
2014-09-04 3:56 ` Shawn Guo
2014-09-04 22:50 ` Fabio Estevam
2014-09-04 22:50 ` Fabio Estevam
[not found] ` <CAOMZO5BOfsvrH3ijxKwyGemEW-B60n-+4wpDZ5xfC98efM469w-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2014-09-04 23:37 ` Anson.Huang-KZfg59tc24xl57MIdRCFDg [this message]
2014-09-04 23:37 ` Anson.Huang at freescale.com
[not found] ` <9B0C19C6-6C3B-47DC-9DC4-5BD42CE294A4-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
2014-09-04 23:42 ` Fabio Estevam
2014-09-04 23:42 ` Fabio Estevam
2014-09-05 0:35 ` Shawn Guo
2014-09-05 0:35 ` Shawn Guo
2014-09-05 3:32 ` Anson.Huang
2014-09-05 3:32 ` Anson.Huang at freescale.com
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