[+cc Rafael, since I used generic PM as an example]
On Wed, Dec 08, 2021 at 09:47:56AM +0100, Greg KH wrote:
On Wed, Dec 08, 2021 at 08:43:53AM +0000, Lee Jones wrote:
On Wed, 08 Dec 2021, Greg KH wrote:
On Wed, Dec 08, 2021 at 09:03:16AM +0200, Leon Romanovsky wrote:
On Tue, Dec 07, 2021 at 09:14:44AM -0800, David E. Box wrote:
Adds get/set driver data helpers for auxiliary devices.
Signed-off-by: David E. Box david.e.box@linux.intel.com Reviewed-by: Mark Gross markgross@kernel.org
V2
- No changes
include/linux/auxiliary_bus.h | 10 ++++++++++ 1 file changed, 10 insertions(+)
I would really like to see an explanation why such obfuscation is really needed. dev_*_drvdata() is a standard way to access driver data.
I wouldn't call it obfuscation, but it does looks like abstraction for the sake of abstraction, which I usually push back on. What are the technical benefits over using the dev_*() variant?
See my response at: https://lore.kernel.org/r/YbBwOb6JvWkT3JWI@kroah.com for why it is a good thing to do.
In short, driver authors should not have to worry about mixing bus-specific and low-level driver core functions.
In the very common situation of PCI drivers that use generic power management, authors *do* have to use both (example from [1]):
ioh_gpio_probe(struct pci_dev *pdev) # pci_driver.probe() pci_set_drvdata(pdev, chip);
ioh_gpio_remove(struct pci_dev *pdev) # pci_driver.remove() struct ioh_gpio *chip = pci_get_drvdata(pdev);
ioh_gpio_suspend(struct device *dev) # pci_driver.driver.pm.suspend() struct ioh_gpio *chip = dev_get_drvdata(dev); <--
The pci_driver methods receive a struct pci_dev and use the pci_get_drvdata() wrapper.
The generic power management methods receive a struct device and use the underlying dev_get_drvdata().
It's kind of ugly that readers have to know that pci_get_drvdata() gives you the same thing as dev_get_drvdata().
I guess the generic PM methods could do something like:
pci_get_drvdata(to_pci_dev(dev));
but that seems a little bit circuitous. It's slightly wordier, but I might prefer to just use this everywhere and skip the pci_* wrappers:
dev_get_drvdata(&pdev->dev);
Bjorn
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/driv...