Hi Jean I see, thank you very much. Best Regards chunhao -----Original Message----- From: Jean Delvare [mailto:khali at linux-fr.org] Sent: 2004??11??24?? 17:29 To: PI14 HUANG0; sensors at Stimpy.netroedge.com Cc: PI10 LHHsu; PI14 DZSHEN Subject: RE: New chip driver development plan to Lm_sensors Hi Chunhao, > I'm writing a new driver for w83792D, which is w83792d.c,using > w83781d.c as my reference, deleting the codes related with ISA except > two places, because 792D will only be on I2C. Sounds good :) > But I have two questions about w83792d driver now. > (1) Can I delete the following codes? > static unsigned int normal_isa[] = { 0x0290, SENSORS_ISA_END }; > static unsigned int normal_isa_range[] = { SENSORS_ISA_END }; > I guess the above two sentences are useless, but I'm not very > sure about it's function, can you tell me whether I can delete > them or not? No you can't. The i2c-core needs them. Simply remove the address and leave: static unsigned int normal_isa[] = { SENSORS_ISA_END }; static unsigned int normal_isa_range[] = { SENSORS_ISA_END }; This will let the core know that it should not attempt to use your driver for the ISA bus. This is what's done in other i2c-only drivers (such as lm90.c for example). > (2) When you are free, can you give me some general explanation > of the member "last_updated" of struct w83792d_data? > > What I need to do is just keep all the codes related with > "w83792d_data->last_updated" in w83781d.c > Is that right? Yes, keep it. This is something common to (almost) all drivers. The idea is to remember when the chip registers where last read, and force a little delay (typically between 0.5 and 2 seconds depending on the chip) before the driver is allowed to read them all again. This leaves some time for the chip to sample the voltages, temperatures etc. Not all chips do need it, but some chips stop sampling when there is traffic on the I2C interface so we have to do that. Also, since regular users can request data from the driver, it is a good safety that this won't generate I2C traffic each time. If we were really reading the registers each time, then any user could overflow the I2C bus and possibly cause trouble to the system (such as alarm conditions not triggering as needed). So last_updated stores the last time the registers were updated. It is set at the end of the update function. At the beginning of the update function we compare with the current time and if less than the defined delay (usually expressed as x * HZ where HZ means 1 second) has passed since the last update, then we do not read the registers and use the previously read values instead. Jean ===========================================================================================The privileged confidential information contained in this email is intended for use only by the addressees as indicated by the original author of this email. If you are not the addressee indicated in this email or are not responsible for delivery of the email to such person, please kindly reply the sender indicating accordingly and delete all copies of it from your computer and network server immediately. We thank you for your cooperation. It is advisable that any unauthorized use of confidential information of Winbond is strictly prohibited; and any information in this email that does not relate to the official business of Winbond shall be deemed as neither given nor endorsed by Winbond.===========================================================================================If your computer is unable to decode Chinese font, please ignore the following message. They essentially repea! t the English statement above.???H???????t?????q?l???]???????K?????T, ?????v???o?H?H???w?????H?H???\????. ?????z???D?Q???w?????H?H???]???????]?b???g???v?????????U???????H??, ???z?i?????o?H?H?????Y?N?H???q?q???P???????A???????H????. ?????z???X?@, ?????????P??. ?S??????, ???????g???v?????????????q?l?????K???T???????O?Q?Y???T????. ?H???P?????q?l???~?L???????e,???o?????????q?l?????????N??.
