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Date: Thu, 22 Jan 2015 12:57:08 +0800
From: Caesar Wang <sasukewxt@....com>
To: Daniel Kurtz <djkurtz@...omium.org>,
Caesar Wang <caesar.wang@...k-chips.com>
CC: Heiko Stuebner <heiko@...ech.de>, linux-pm@...r.kernel.org,
Dmitry Torokhov <dmitry.torokhov@...il.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Eduardo Valentin <edubezval@...il.com>,
"open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
Zhang Rui <rui.zhang@...el.com>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
Caesar Wang <wxt@...k-chips.com>
Subject: Re: [PATCH v3] thermal: rockchip: make temperature reporting much
more accurate
在 2015年01月22日 12:25, Daniel Kurtz 写道:
> 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.
Maybe "return -EAGAIN"
>
>>>> 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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