Messages in this thread |  | | Subject | Re: [PATCH v2 2/3] scsi: ufs: Modulize ufs-bsg | From | Bart Van Assche <> | Date | Mon, 16 Dec 2019 09:22:21 -0800 |
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On 12/15/19 8:36 PM, cang@codeaurora.org wrote: > On 2019-12-16 05:49, Bart Van Assche wrote: >> On 2019-12-11 22:37, Bjorn Andersson wrote: >>> It's the asymmetry that I don't like. >>> >>> Perhaps if you instead make ufshcd platform_device_register_data() the >>> bsg device you would solve the probe ordering, the remove will be >>> symmetric and module autoloading will work as well (although then you >>> need a MODULE_ALIAS of platform:device-name). >> >> Hi Bjorn, >> >> From Documentation/driver-api/driver-model/platform.rst: >> "Platform devices are devices that typically appear as autonomous >> entities in the system. This includes legacy port-based devices and >> host bridges to peripheral buses, and most controllers integrated >> into system-on-chip platforms. What they usually have in common >> is direct addressing from a CPU bus. Rarely, a platform_device will >> be connected through a segment of some other kind of bus; but its >> registers will still be directly addressable." >> >> Do you agree that the above description is not a good match for the >> ufs-bsg kernel module? > > I missed this one. > How about making it a plain device and add it from ufs driver?
Hi Can,
Since the ufs_bsg kernel module already creates one device node under /dev/bsg for each UFS host I don't think that we need to create any additional device nodes for ufs-bsg devices. My proposal is to modify the original patch 2/3 from this series as follows: * Use module_init() instead of late_initcall_sync(). * Remove the ufshcd_get_hba_list_lock() and ufshcd_put_hba_list_unlock() functions. * Implement a notification mechanism in the UFS core that invokes a callback function after an UFS host has been created and also after an UFS host has been removed. * Register for these notifications from inside the ufs-bsg driver. * During registration for notifications, invoke the UFS host creation callback function for all known UFS hosts. * If the UFS core is unloaded, invoke the UFS host removal callback function for all known UFS hosts.
I think there are several examples of similar notification mechanisms in the Linux kernel, e.g. the probe and remove callback functions in struct pci_driver.
Bart.
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