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([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2cacd3e5a87sm7163531a91.14.2024.07.15.19.25.14 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 15 Jul 2024 19:25:15 -0700 (PDT) Sender: Guenter Roeck Message-ID: Date: Mon, 15 Jul 2024 19:25:14 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/5] hwmon: pmbus: Implement generic bus access delay To: Patrick Rudolph , linux-kernel@vger.kernel.org Cc: Jean Delvare , linux-hwmon@vger.kernel.org References: <20240715073105.594221-1-patrick.rudolph@9elements.com> Content-Language: en-US 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= In-Reply-To: <20240715073105.594221-1-patrick.rudolph@9elements.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 7/15/24 00:30, Patrick Rudolph wrote: > Some drivers, like the max15301 or zl6100, are intentionally delaying > SMBus communications, to prevent transmission errors. As this is necessary > on additional PMBus compatible devices, implement a generic delay mechanism > in the pmbus core. > > Introduces two delay settings in the pmbus_driver_info struct, one applies > to every SMBus transaction and the other is for write transaction only. > Once set by the driver the SMBus traffic, using the generic pmbus access > helpers, is automatically delayed when necessary. > > The two settings are: > access_delay: > - Unit in microseconds > - Stores the accessed timestamp after every SMBus access > - Delays when necessary before the next SMBus access > > write_delay: > - Unit in microseconds > - Stores the written timestamp after a write SMBus access > - Delays when necessary before the next SMBus access > > This allows to drop the custom delay code from the drivers and easily > introduce this feature in additional pmbus drivers. > > Signed-off-by: Patrick Rudolph > --- > drivers/hwmon/pmbus/pmbus.h | 10 ++++ > drivers/hwmon/pmbus/pmbus_core.c | 92 +++++++++++++++++++++++++++++--- > 2 files changed, 96 insertions(+), 6 deletions(-) > > diff --git a/drivers/hwmon/pmbus/pmbus.h b/drivers/hwmon/pmbus/pmbus.h > index fb442fae7b3e..5d5dc774187b 100644 > --- a/drivers/hwmon/pmbus/pmbus.h > +++ b/drivers/hwmon/pmbus/pmbus.h > @@ -466,6 +466,16 @@ struct pmbus_driver_info { > > /* custom attributes */ > const struct attribute_group **groups; > + > + /* > + * Some chips need a little delay between SMBus communication. When > + * set, the generic PMBus helper functions will wait if necessary > + * to meet this requirement. The access delay is honored after > + * every SMBus operation. The write delay is only honored after > + * SMBus write operations. > + */ > + int access_delay; /* in microseconds */ > + int write_delay; /* in microseconds */ > }; > > /* Regulator ops */ > diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c > index cb4c65a7f288..5cb093c898a1 100644 > --- a/drivers/hwmon/pmbus/pmbus_core.c > +++ b/drivers/hwmon/pmbus/pmbus_core.c > @@ -7,6 +7,7 @@ > */ > > #include > +#include > #include > #include > #include > @@ -108,6 +109,8 @@ struct pmbus_data { > > int vout_low[PMBUS_PAGES]; /* voltage low margin */ > int vout_high[PMBUS_PAGES]; /* voltage high margin */ > + ktime_t write_time; /* Last SMBUS write timestamp */ > + ktime_t access_time; /* Last SMBUS access timestamp */ > }; > > struct pmbus_debugfs_entry { > @@ -158,6 +161,39 @@ void pmbus_set_update(struct i2c_client *client, u8 reg, bool update) > } > EXPORT_SYMBOL_NS_GPL(pmbus_set_update, PMBUS); > > +/* Some chips need a delay between accesses. */ > +static inline void pmbus_optional_wait(struct i2c_client *client) Also, please drop the inline here and below to let the compiler decide if it wants to inline or not. Thanks, Guenter > +{ > + struct pmbus_data *data = i2c_get_clientdata(client); > + const struct pmbus_driver_info *info = data->info; > + s64 delta; > + > + if (info->access_delay) { > + delta = ktime_us_delta(ktime_get(), data->access_time); > + > + if (delta < info->access_delay) > + udelay(info->access_delay - delta); > + } else if (info->write_delay) { > + delta = ktime_us_delta(ktime_get(), data->write_time); > + > + if (delta < info->write_delay) > + udelay(info->write_delay - delta); > + } > +} > + > +/* Sets the last accessed timestamp for pmbus_optional_wait */ > +static inline void pmbus_update_ts(struct i2c_client *client, bool write_op) > +{ > + struct pmbus_data *data = i2c_get_clientdata(client); > + const struct pmbus_driver_info *info = data->info; > + > + if (info->access_delay) { > + data->access_time = ktime_get(); > + } else if (info->write_delay && write_op) { > + data->write_time = ktime_get(); > + } > +} > + > int pmbus_set_page(struct i2c_client *client, int page, int phase) > { > struct pmbus_data *data = i2c_get_clientdata(client); > @@ -168,11 +204,15 @@ int pmbus_set_page(struct i2c_client *client, int page, int phase) > > if (!(data->info->func[page] & PMBUS_PAGE_VIRTUAL) && > data->info->pages > 1 && page != data->currpage) { > + pmbus_optional_wait(client); > rv = i2c_smbus_write_byte_data(client, PMBUS_PAGE, page); > + pmbus_update_ts(client, true); > if (rv < 0) > return rv; > > + pmbus_optional_wait(client); > rv = i2c_smbus_read_byte_data(client, PMBUS_PAGE); > + pmbus_update_ts(client, false); > if (rv < 0) > return rv; > > @@ -183,8 +223,10 @@ int pmbus_set_page(struct i2c_client *client, int page, int phase) > > if (data->info->phases[page] && data->currphase != phase && > !(data->info->func[page] & PMBUS_PHASE_VIRTUAL)) { > + pmbus_optional_wait(client); > rv = i2c_smbus_write_byte_data(client, PMBUS_PHASE, > phase); > + pmbus_update_ts(client, true); > if (rv) > return rv; > } > @@ -202,7 +244,11 @@ int pmbus_write_byte(struct i2c_client *client, int page, u8 value) > if (rv < 0) > return rv; > > - return i2c_smbus_write_byte(client, value); > + pmbus_optional_wait(client); > + rv = i2c_smbus_write_byte(client, value); > + pmbus_update_ts(client, true); > + > + return rv; > } > EXPORT_SYMBOL_NS_GPL(pmbus_write_byte, PMBUS); > > @@ -233,7 +279,11 @@ int pmbus_write_word_data(struct i2c_client *client, int page, u8 reg, > if (rv < 0) > return rv; > > - return i2c_smbus_write_word_data(client, reg, word); > + pmbus_optional_wait(client); > + rv = i2c_smbus_write_word_data(client, reg, word); > + pmbus_update_ts(client, true); > + > + return rv; > } > EXPORT_SYMBOL_NS_GPL(pmbus_write_word_data, PMBUS); > > @@ -351,7 +401,11 @@ int pmbus_read_word_data(struct i2c_client *client, int page, int phase, u8 reg) > if (rv < 0) > return rv; > > - return i2c_smbus_read_word_data(client, reg); > + pmbus_optional_wait(client); > + rv = i2c_smbus_read_word_data(client, reg); > + pmbus_update_ts(client, false); > + > + return rv; > } > EXPORT_SYMBOL_NS_GPL(pmbus_read_word_data, PMBUS); > > @@ -410,7 +464,11 @@ int pmbus_read_byte_data(struct i2c_client *client, int page, u8 reg) > if (rv < 0) > return rv; > > - return i2c_smbus_read_byte_data(client, reg); > + pmbus_optional_wait(client); > + rv = i2c_smbus_read_byte_data(client, reg); > + pmbus_update_ts(client, false); > + > + return rv; > } > EXPORT_SYMBOL_NS_GPL(pmbus_read_byte_data, PMBUS); > > @@ -422,7 +480,11 @@ int pmbus_write_byte_data(struct i2c_client *client, int page, u8 reg, u8 value) > if (rv < 0) > return rv; > > - return i2c_smbus_write_byte_data(client, reg, value); > + pmbus_optional_wait(client); > + rv = i2c_smbus_write_byte_data(client, reg, value); > + pmbus_update_ts(client, true); > + > + return rv; > } > EXPORT_SYMBOL_NS_GPL(pmbus_write_byte_data, PMBUS); > > @@ -454,7 +516,11 @@ static int pmbus_read_block_data(struct i2c_client *client, int page, u8 reg, > if (rv < 0) > return rv; > > - return i2c_smbus_read_block_data(client, reg, data_buf); > + pmbus_optional_wait(client); > + rv = i2c_smbus_read_block_data(client, reg, data_buf); > + pmbus_update_ts(client, false); > + > + return rv; > } > > static struct pmbus_sensor *pmbus_find_sensor(struct pmbus_data *data, int page, > @@ -2450,9 +2516,11 @@ static int pmbus_read_coefficients(struct i2c_client *client, > data.block[1] = attr->reg; > data.block[2] = 0x01; > > + pmbus_optional_wait(client); > rv = i2c_smbus_xfer(client->adapter, client->addr, client->flags, > I2C_SMBUS_WRITE, PMBUS_COEFFICIENTS, > I2C_SMBUS_BLOCK_PROC_CALL, &data); > + pmbus_update_ts(client, false); > > if (rv < 0) > return rv; > @@ -2604,7 +2672,10 @@ static int pmbus_init_common(struct i2c_client *client, struct pmbus_data *data, > > /* Enable PEC if the controller and bus supports it */ > if (!(data->flags & PMBUS_NO_CAPABILITY)) { > + pmbus_optional_wait(client); > ret = i2c_smbus_read_byte_data(client, PMBUS_CAPABILITY); > + pmbus_update_ts(client, false); > + > if (ret >= 0 && (ret & PB_CAPABILITY_ERROR_CHECK)) { > if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_PEC)) > client->flags |= I2C_CLIENT_PEC; > @@ -2617,10 +2688,16 @@ static int pmbus_init_common(struct i2c_client *client, struct pmbus_data *data, > * Bail out if both registers are not supported. > */ > data->read_status = pmbus_read_status_word; > + pmbus_optional_wait(client); > ret = i2c_smbus_read_word_data(client, PMBUS_STATUS_WORD); > + pmbus_update_ts(client, false); > + > if (ret < 0 || ret == 0xffff) { > data->read_status = pmbus_read_status_byte; > + pmbus_optional_wait(client); > ret = i2c_smbus_read_byte_data(client, PMBUS_STATUS_BYTE); > + pmbus_update_ts(client, false); > + > if (ret < 0 || ret == 0xff) { > dev_err(dev, "PMBus status register not found\n"); > return -ENODEV; > @@ -2635,7 +2712,10 @@ static int pmbus_init_common(struct i2c_client *client, struct pmbus_data *data, > * limit registers need to be disabled. > */ > if (!(data->flags & PMBUS_NO_WRITE_PROTECT)) { > + pmbus_optional_wait(client); > ret = i2c_smbus_read_byte_data(client, PMBUS_WRITE_PROTECT); > + pmbus_update_ts(client, false); > + > if (ret > 0 && (ret & PB_WP_ANY)) > data->flags |= PMBUS_WRITE_PROTECTED | PMBUS_SKIP_STATUS_CHECK; > }