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Tue, 06 Apr 2021 11:42:09 -0700 (PDT) Sender: Guenter Roeck Subject: Re: [PATCH v2] hwmon: (sbtsi) Don't read sensor more than once if it doesn't respond To: Konstantin Aladyshev Cc: kunyi@google.com, Jean Delvare , linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org References: <20210406181624.713-1-aladyshev22@gmail.com> From: Guenter Roeck Autocrypt: addr=linux@roeck-us.net; keydata= xsFNBE6H1WcBEACu6jIcw5kZ5dGeJ7E7B2uweQR/4FGxH10/H1O1+ApmcQ9i87XdZQiB9cpN RYHA7RCEK2dh6dDccykQk3bC90xXMPg+O3R+C/SkwcnUak1UZaeK/SwQbq/t0tkMzYDRxfJ7 nyFiKxUehbNF3r9qlJgPqONwX5vJy4/GvDHdddSCxV41P/ejsZ8PykxyJs98UWhF54tGRWFl 7i1xvaDB9lN5WTLRKSO7wICuLiSz5WZHXMkyF4d+/O5ll7yz/o/JxK5vO/sduYDIlFTvBZDh gzaEtNf5tQjsjG4io8E0Yq0ViobLkS2RTNZT8ICq/Jmvl0SpbHRvYwa2DhNsK0YjHFQBB0FX IdhdUEzNefcNcYvqigJpdICoP2e4yJSyflHFO4dr0OrdnGLe1Zi/8Xo/2+M1dSSEt196rXaC kwu2KgIgmkRBb3cp2vIBBIIowU8W3qC1+w+RdMUrZxKGWJ3juwcgveJlzMpMZNyM1jobSXZ0 VHGMNJ3MwXlrEFPXaYJgibcg6brM6wGfX/LBvc/haWw4yO24lT5eitm4UBdIy9pKkKmHHh7s jfZJkB5fWKVdoCv/omy6UyH6ykLOPFugl+hVL2Prf8xrXuZe1CMS7ID9Lc8FaL1ROIN/W8Vk BIsJMaWOhks//7d92Uf3EArDlDShwR2+D+AMon8NULuLBHiEUQARAQABzTJHdWVudGVyIFJv ZWNrIChMaW51eCBhY2NvdW50KSA8bGludXhAcm9lY2stdXMubmV0PsLBgQQTAQIAKwIbAwYL CQgHAwIGFQgCCQoLBBYCAwECHgECF4ACGQEFAlVcphcFCRmg06EACgkQyx8mb86fmYFg0RAA nzXJzuPkLJaOmSIzPAqqnutACchT/meCOgMEpS5oLf6xn5ySZkl23OxuhpMZTVX+49c9pvBx hpvl5bCWFu5qC1jC2eWRYU+aZZE4sxMaAGeWenQJsiG9lP8wkfCJP3ockNu0ZXXAXwIbY1O1 c+l11zQkZw89zNgWgKobKzrDMBFOYtAh0pAInZ9TSn7oA4Ctejouo5wUugmk8MrDtUVXmEA9 7f9fgKYSwl/H7dfKKsS1bDOpyJlqhEAH94BHJdK/b1tzwJCFAXFhMlmlbYEk8kWjcxQgDWMu GAthQzSuAyhqyZwFcOlMCNbAcTSQawSo3B9yM9mHJne5RrAbVz4TWLnEaX8gA5xK3uCNCeyI sqYuzA4OzcMwnnTASvzsGZoYHTFP3DQwf2nzxD6yBGCfwNGIYfS0i8YN8XcBgEcDFMWpOQhT Pu3HeztMnF3HXrc0t7e5rDW9zCh3k2PA6D2NV4fews9KDFhLlTfCVzf0PS1dRVVWM+4jVl6l HRIAgWp+2/f8dx5vPc4Ycp4IsZN0l1h9uT7qm1KTwz+sSl1zOqKD/BpfGNZfLRRxrXthvvY8 BltcuZ4+PGFTcRkMytUbMDFMF9Cjd2W9dXD35PEtvj8wnEyzIos8bbgtLrGTv/SYhmPpahJA l8hPhYvmAvpOmusUUyB30StsHIU2LLccUPPOwU0ETofVZwEQALlLbQeBDTDbwQYrj0gbx3bq 7kpKABxN2MqeuqGr02DpS9883d/t7ontxasXoEz2GTioevvRmllJlPQERVxM8gQoNg22twF7 pB/zsrIjxkE9heE4wYfN1AyzT+AxgYN6f8hVQ7Nrc9XgZZe+8IkuW/Nf64KzNJXnSH4u6nJM J2+Dt274YoFcXR1nG76Q259mKwzbCukKbd6piL+VsT/qBrLhZe9Ivbjq5WMdkQKnP7gYKCAi pNVJC4enWfivZsYupMd9qn7Uv/oCZDYoBTdMSBUblaLMwlcjnPpOYK5rfHvC4opxl+P/Vzyz 6WC2TLkPtKvYvXmdsI6rnEI4Uucg0Au/Ulg7aqqKhzGPIbVaL+U0Wk82nz6hz+WP2ggTrY1w ZlPlRt8WM9w6WfLf2j+PuGklj37m+KvaOEfLsF1v464dSpy1tQVHhhp8LFTxh/6RWkRIR2uF I4v3Xu/k5D0LhaZHpQ4C+xKsQxpTGuYh2tnRaRL14YMW1dlI3HfeB2gj7Yc8XdHh9vkpPyuT nY/ZsFbnvBtiw7GchKKri2gDhRb2QNNDyBnQn5mRFw7CyuFclAksOdV/sdpQnYlYcRQWOUGY HhQ5eqTRZjm9z+qQe/T0HQpmiPTqQcIaG/edgKVTUjITfA7AJMKLQHgp04Vylb+G6jocnQQX JqvvP09whbqrABEBAAHCwWUEGAECAA8CGwwFAlVcpi8FCRmg08MACgkQyx8mb86fmYHNRQ/+ J0OZsBYP4leJvQF8lx9zif+v4ZY/6C9tTcUv/KNAE5leyrD4IKbnV4PnbrVhjq861it/zRQW cFpWQszZyWRwNPWUUz7ejmm9lAwPbr8xWT4qMSA43VKQ7ZCeTQJ4TC8kjqtcbw41SjkjrcTG wF52zFO4bOWyovVAPncvV9eGA/vtnd3xEZXQiSt91kBSqK28yjxAqK/c3G6i7IX2rg6pzgqh hiH3/1qM2M/LSuqAv0Rwrt/k+pZXE+B4Ud42hwmMr0TfhNxG+X7YKvjKC+SjPjqp0CaztQ0H nsDLSLElVROxCd9m8CAUuHplgmR3seYCOrT4jriMFBtKNPtj2EE4DNV4s7k0Zy+6iRQ8G8ng QjsSqYJx8iAR8JRB7Gm2rQOMv8lSRdjva++GT0VLXtHULdlzg8VjDnFZ3lfz5PWEOeIMk7Rj trjv82EZtrhLuLjHRCaG50OOm0hwPSk1J64R8O3HjSLdertmw7eyAYOo4RuWJguYMg5DRnBk WkRwrSuCn7UG+qVWZeKEsFKFOkynOs3pVbcbq1pxbhk3TRWCGRU5JolI4ohy/7JV1TVbjiDI HP/aVnm6NC8of26P40Pg8EdAhajZnHHjA7FrJXsy3cyIGqvg9os4rNkUWmrCfLLsZDHD8FnU mDW4+i+XlNFUPUYMrIKi9joBhu18ssf5i5Q= Message-ID: <0ba1d271-78cd-c30a-e662-97ab8ba6451a@roeck-us.net> Date: Tue, 6 Apr 2021 11:42:07 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20210406181624.713-1-aladyshev22@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-hwmon@vger.kernel.org On 4/6/21 11:16 AM, Konstantin Aladyshev wrote: > SBTSI sensors don't work when the CPU is off. > In this case every 'i2c_smbus_read_byte_data' function would fail > by a timeout. > Currently temp1_max/temp1_min file reads can cause two such timeouts > for every read. > Restructure code so there will be no more than one timeout for every > read operation. > > Signed-off-by: Konstantin Aladyshev > --- > Changes in v2: > - Fix typo in a commit message > - Don't swap temp_int/temp_dec checks at the end of the 'sbtsi_read' function > This doesn't explain the reason for the extra read operation for limits. Preventing a second read in error cases is not an argument for adding an extra read for non-error cases. Guenter > drivers/hwmon/sbtsi_temp.c | 55 +++++++++++++++++++------------------- > 1 file changed, 27 insertions(+), 28 deletions(-) > > diff --git a/drivers/hwmon/sbtsi_temp.c b/drivers/hwmon/sbtsi_temp.c > index e35357c48b8e..4ae48635bb31 100644 > --- a/drivers/hwmon/sbtsi_temp.c > +++ b/drivers/hwmon/sbtsi_temp.c > @@ -74,48 +74,47 @@ static int sbtsi_read(struct device *dev, enum hwmon_sensor_types type, > u32 attr, int channel, long *val) > { > struct sbtsi_data *data = dev_get_drvdata(dev); > + u8 temp_int_reg, temp_dec_reg; > s32 temp_int, temp_dec; > int err; > > switch (attr) { > case hwmon_temp_input: > - /* > - * ReadOrder bit specifies the reading order of integer and > - * decimal part of CPU temp for atomic reads. If bit == 0, > - * reading integer part triggers latching of the decimal part, > - * so integer part should be read first. If bit == 1, read > - * order should be reversed. > - */ > - err = i2c_smbus_read_byte_data(data->client, SBTSI_REG_CONFIG); > - if (err < 0) > - return err; > - > - mutex_lock(&data->lock); > - if (err & BIT(SBTSI_CONFIG_READ_ORDER_SHIFT)) { > - temp_dec = i2c_smbus_read_byte_data(data->client, SBTSI_REG_TEMP_DEC); > - temp_int = i2c_smbus_read_byte_data(data->client, SBTSI_REG_TEMP_INT); > - } else { > - temp_int = i2c_smbus_read_byte_data(data->client, SBTSI_REG_TEMP_INT); > - temp_dec = i2c_smbus_read_byte_data(data->client, SBTSI_REG_TEMP_DEC); > - } > - mutex_unlock(&data->lock); > + temp_int_reg = SBTSI_REG_TEMP_INT; > + temp_dec_reg = SBTSI_REG_TEMP_DEC; > break; > case hwmon_temp_max: > - mutex_lock(&data->lock); > - temp_int = i2c_smbus_read_byte_data(data->client, SBTSI_REG_TEMP_HIGH_INT); > - temp_dec = i2c_smbus_read_byte_data(data->client, SBTSI_REG_TEMP_HIGH_DEC); > - mutex_unlock(&data->lock); > + temp_int_reg = SBTSI_REG_TEMP_HIGH_INT; > + temp_dec_reg = SBTSI_REG_TEMP_HIGH_DEC; > break; > case hwmon_temp_min: > - mutex_lock(&data->lock); > - temp_int = i2c_smbus_read_byte_data(data->client, SBTSI_REG_TEMP_LOW_INT); > - temp_dec = i2c_smbus_read_byte_data(data->client, SBTSI_REG_TEMP_LOW_DEC); > - mutex_unlock(&data->lock); > + temp_int_reg = SBTSI_REG_TEMP_LOW_INT; > + temp_dec_reg = SBTSI_REG_TEMP_LOW_DEC; > break; > default: > return -EINVAL; > } > > + /* > + * ReadOrder bit specifies the reading order of integer and > + * decimal part of CPU temp for atomic reads. If bit == 0, > + * reading integer part triggers latching of the decimal part, > + * so integer part should be read first. If bit == 1, read > + * order should be reversed. > + */ > + err = i2c_smbus_read_byte_data(data->client, SBTSI_REG_CONFIG); > + if (err < 0) > + return err; > + > + mutex_lock(&data->lock); > + if (err & BIT(SBTSI_CONFIG_READ_ORDER_SHIFT)) { > + temp_dec = i2c_smbus_read_byte_data(data->client, temp_dec_reg); > + temp_int = i2c_smbus_read_byte_data(data->client, temp_int_reg); > + } else { > + temp_int = i2c_smbus_read_byte_data(data->client, temp_int_reg); > + temp_dec = i2c_smbus_read_byte_data(data->client, temp_dec_reg); > + } > + mutex_unlock(&data->lock); > > if (temp_int < 0) > return temp_int; >