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Message-ID: <CAGS+omDdbUBn5swOZ23K3MpjzV3UMk3xABLWxj1SFE+s=FcHQA@mail.gmail.com>
Date: Thu, 22 Jan 2015 12:25:00 +0800
From: Daniel Kurtz <djkurtz@...omium.org>
To: Caesar Wang <caesar.wang@...k-chips.com>
Cc: Caesar Wang <wxt@...k-chips.com>, Heiko Stuebner <heiko@...ech.de>,
Zhang Rui <rui.zhang@...el.com>,
Eduardo Valentin <edubezval@...il.com>,
Dmitry Torokhov <dmitry.torokhov@...il.com>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
linux-pm@...r.kernel.org,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3] thermal: rockchip: make temperature reporting much
more accurate
On Thu, Jan 22, 2015 at 12:21 PM, Caesar Wang
<caesar.wang@...k-chips.com> wrote:
>
> 在 2015年01月22日 12:01, Daniel Kurtz 写道:
>
>> On Thu, Jan 22, 2015 at 1:29 AM, Caesar Wang <wxt@...k-chips.com> wrote:
>>>
>>> In general, the kernel should report temperature readings exactly as
>>> reported by the hardware. The cpu / gpu thermal driver works in 5 degree
>>> increments,but we ought to do more accurate. The temperature will do
>>> linear interpolation between the entries in the table.
>>>
>>> Test= $md5sum /dev/zero &
>>> $while true; do grep "" /sys/class/thermal/thermal_zone[1-2]/temp;
>>> sleep .5; done
>>>
>>> e.g. We can get the result as follows:
>>> /sys/class/thermal/thermal_zone1/temp:39994
>>> /sys/class/thermal/thermal_zone2/temp:39086
>>> /sys/class/thermal/thermal_zone1/temp:39994
>>> /sys/class/thermal/thermal_zone2/temp:39540
>>> /sys/class/thermal/thermal_zone1/temp:39540
>>> /sys/class/thermal/thermal_zone2/temp:39540
>>> /sys/class/thermal/thermal_zone1/temp:39540
>>> /sys/class/thermal/thermal_zone2/temp:39994
>>>
>>> Signed-off-by: Caesar Wang <wxt@...k-chips.com>
>>> Reviewed-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
>>>
>>> ---
>>>
>>> Changes in v3:
>>> Suggested-by Daniel Kurtz,
>>> the check doesn't reject "code == 0xfff"
>>> Fixed in rk_tsadcv2_code_to_temp(u32 code)
>>>
>>> Changes in v2:
>>> Reviewed-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
>>>
>>> drivers/thermal/rockchip_thermal.c | 32
>>> ++++++++++++++++++++++----------
>>> 1 file changed, 22 insertions(+), 10 deletions(-)
>>>
>>> diff --git a/drivers/thermal/rockchip_thermal.c
>>> b/drivers/thermal/rockchip_thermal.c
>>> index 1bcddfc..ce18007 100644
>>> --- a/drivers/thermal/rockchip_thermal.c
>>> +++ b/drivers/thermal/rockchip_thermal.c
>>> @@ -193,19 +193,22 @@ static u32 rk_tsadcv2_temp_to_code(long temp)
>>>
>>> static long rk_tsadcv2_code_to_temp(u32 code)
>>> {
>>> - int high, low, mid;
>>> -
>>> - low = 0;
>>> - high = ARRAY_SIZE(v2_code_table) - 1;
>>> - mid = (high + low) / 2;
>>> + unsigned int low = 0;
>>> + unsigned int high = ARRAY_SIZE(v2_code_table) - 1;
>>> + unsigned int mid = (low + high) / 2;
>>> + unsigned int num;
>>> + unsigned long denom;
>>>
>>> + /* No code available, return callback */
>>> if (code > v2_code_table[low].code || code <
>>> v2_code_table[high].code)
>>> - return 125000; /* No code available, return max
>>> temperature */
>>> + return rk_tsadcv2_code_to_temp(code);
>>
>> Isn't this an infinite recursion?
>
>
> No, I think we can try check if it is happened.
> Maybe we can return a warning/error for it.
I mean, if the 'if' condition is true, then this will just call the
same function again with the same code, and again, and again...
Just return an error code here, -ENOENT maybe?
I am not sure what error code is appropriate.
>
>>> while (low <= high) {
>>> - if (code >= v2_code_table[mid].code && code <
>>> - v2_code_table[mid - 1].code)
>>> - return v2_code_table[mid].temp;
>>> + if (code >= v2_code_table[mid].code &&
>>> + code < v2_code_table[mid - 1].code)
>>> + break;
>>> + else if (code == TSADCV2_DATA_MASK)
>>> + break;
>>> else if (code < v2_code_table[mid].code)
>>> low = mid + 1;
>>> else
>>> @@ -213,7 +216,16 @@ static long rk_tsadcv2_code_to_temp(u32 code)
>>> mid = (low + high) / 2;
>>> }
>>>
>>> - return 125000;
>>> + /*
>>> + * The 5C granularity provided by the table is too much. Let's
>>> + * assume that the relationship between sensor readings and
>>> + * temperature between 2 table entries is linear and interpolate
>>> + * to produce less granular result.
>>> + */
>>> + num = v2_code_table[mid].temp - v2_code_table[mid - 1].temp;
>>> + num *= v2_code_table[mid - 1].code - code;
>>> + denom = v2_code_table[mid - 1].code - v2_code_table[mid].code;
>>> + return v2_code_table[mid - 1].temp + (num / denom);
>>> }
>>>
>>> /**
>>> --
>>> 1.9.1
>>>
>>>
>>
>>
>
> --
> Best regards
> Caesar Wang (王晓腾)
> 福州瑞芯微电子有限公司
> Fuzhou Rockchip Electronics Co.Ltd
> 福建省福州市铜盘路软件大道89号软件园A区18号楼(350003)
> Addr:No.18 Building, A District, No.89, software Boulevard Fuzhou,
> Fujian,PRC
> Email:wxt@...k-chips.com
> Tel:+86-591-83991906/07->8221
>
>
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