Hi, I'm trying to support unbinding an AHCI platform device from the ahci_platform driver, so that I can put my entire SoC SATA core into a low power state with no functionality, similar to case 1 here: http://article.gmane.org/gmane.linux.power-management.general/27080 The bind/unbind suggestion is here: http://article.gmane.org/gmane.linux.power-management.general/27093 Right now, ahci_platform doesn't support unbinding due to its use of platform_driver_probe(). I have tried patching it to be a typical module_platform_driver(), including a proper .probe function in the platform_driver struct. This gives me the unbind sysfs hook I'm looking for. However, I'm running into a problem with the AHCI/ATA system. If I power down my core during the "exit" hook in ahci_remove (drivers/ata/ahci_platform.c:212), then the ATA subsystem still tries to perform HW activity via its devres cleanup functions. This obviously causes a bus error, as my core is powered down. In fact, this error occurs with either unbind or rmmod - see below. So: this really comes down to the fact that ATA's devres system is being used in an unsafe way. Typically, devres is just used for SW-only cleanup, right? (DMA buffers, memory, etc.?) The suspect line (libata-core.c:5880): start_dr = devres_alloc(ata_host_stop, 0, GFP_KERNEL); Thanks, Brian --- # rmmod ahci_platform.ko Data bus error, epc == e07c0ca0, ra == e07c0d24 Oops[#1]: ... Call Trace: [<e07c0ca0>] ahci_stop_engine+0x28/0x84 [libahci] [<e07c0d24>] ahci_deinit_port+0x28/0xe8 [libahci] [<e07c0e08>] ahci_port_stop+0x24/0x64 [libahci] [<802dcc28>] ata_host_stop+0x5c/0xc0 [<802b5390>] release_nodes+0x144/0x244 [<802b159c>] __device_release_driver+0x68/0xcc [<802b1fd8>] driver_detach+0xe8/0xf0 [<802b13e0>] bus_remove_driver+0x98/0x128 [<8007b9e4>] sys_delete_module+0x188/0x2d4 [<8000e6fc>] stack_done+0x20/0x40 -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
