Hi, Fabio
can I know why you want to run the new kernel with old dtb?
Sent from Anson's iPhone
> 在 2014年9月5日，6:50，"Fabio Estevam" <festevam@xxxxxxxxx> 写道：
>
>> On Wed, Sep 3, 2014 at 4:36 AM, Anson Huang <b20788@xxxxxxxxxxxxx> 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.
?韬{.n?????%??檩??w?{.n????z谵{???塄}?财??j:+v?? ? ???2??璀??摺?囤??z夸z罐?+?????w棹f
