差異處
這裏顯示兩個版本的差異處。
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cpp:linux_kernel:smbus_controller [2016/01/21 21:54] tony |
cpp:linux_kernel:smbus_controller [2023/06/25 09:48] |
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| - | {{tag>linux}} | ||
| - | ====== 在UEFI-aware OS上遇到的SMBus Controller問題 ====== | ||
| - | ===== Problem ===== | ||
| - | 最近遇到在UEFI-aware的Windows上，SMBus Controller的I/O Space沒被enable的情況，這是發生在Wellsburg的PCH chip。可以透過取得SMBus Controller的PCI Configuration的0x04，確認bit 0(IO space)與bit 1(Memory space)是否為0得知。然而卻一直無法得知這算是BIOS還是OS Driver該去enable的。\\ | ||
| - | \\ | ||
| - | 目前知道並非所有的linux diver都會去enable這個register，而Wellsburg使用到的i2c-i801則會去enable。可以參考[[http://lxr.free-electrons.com/source/drivers/i2c/busses/i2c-i801.c|i2c-i801.c]]的i801_probe，裡面會使用到[[http://lxr.free-electrons.com/source/drivers/pci/pci.c#L1467|pcim_enable_device]]。接著可以trace到以下的code: | ||
| - | <code cpp> | ||
| - | 1388 * pci_enable_device - Initialize device before it's used by a driver. | ||
| - | 1389 * @dev: PCI device to be initialized | ||
| - | 1390 * | ||
| - | 1391 * Initialize device before it's used by a driver. Ask low-level code | ||
| - | 1392 * to enable I/O and memory. Wake up the device if it was suspended. | ||
| - | 1393 * Beware, this function can fail. | ||
| - | 1394 * | ||
| - | 1395 * Note we don't actually enable the device many times if we call | ||
| - | 1396 * this function repeatedly (we just increment the count). | ||
| - | 1397 */ | ||
| - | 1398 int pci_enable_device(struct pci_dev *dev) | ||
| - | 1399 { | ||
| - | 1400 return pci_enable_device_flags(dev, IORESOURCE_MEM | IORESOURCE_IO); | ||
| - | 1401 } | ||
| - | </code> | ||
| - | 至於到底是BIOS要去enable，還是OS driver要去enable，等我找到資料再補充。 | ||
| - | ===== Reference ===== | ||
| - | * [[http://lxr.free-electrons.com/source/drivers/i2c/busses/i2c-i801.c|i2c-i801.c]] | ||
| - | * [[http://www.techbang.com/posts/4359-fully-understand-uefi-bios-theory-and-actual-combat-2-liu-xiudian|UEFI BIOS系統的開機流程]] | ||
| - | ===== ===== | ||
| - | ---- | ||
| - | \\ | ||
| - | ~~DISQUS~~ | ||
