On Wed, Feb 23, 2022 at 12:13:07PM +0100, Greg Kroah-Hartman wrote: > On Wed, Feb 23, 2022 at 01:08:07PM +0200, Andy Shevchenko wrote: > > On Tue, Feb 22, 2022 at 08:02:10AM -0800, Christoph Hellwig wrote: > > > On Tue, Feb 22, 2022 at 10:14:16AM +0100, Jiri Slaby wrote: > > > > On 16. 02. 22, 9:53, Christoph Hellwig wrote: > > > > > On Tue, Feb 15, 2022 at 03:43:59PM +0200, Andy Shevchenko wrote: > > > > > > The pci_iounmap() doesn't cover all the cases where resource should > > > > > > be unmapped. Instead of spreading it more, replace the pci_ioremap_bar() > > > > > > with pcim_iomap() which uses managed resource approach. > > > > > > > > > > pcim_iomap requires the use of ioreadX/iowriteX and thus runtime > > > > > overhead. So in doubt please add a pcim_ioremap_bar instead of forcing > > > > > the legacy iomap/ioread/iowrite API onto modern drivers tht can't > > > > > support legacy port I/O. > > > > > > > > Hmm, the driver combines pci_ioremap_bar with pci_iounmap. pci_iounmap does > > > > the right thing after all, but is that correct? And this driver is not > > > > alone, this shows more: > > > > git grep -E 'pci_iounmap|pci_ioremap_bar' `git grep -l pci_iounmap \`git > > > > grep -l pci_ioremap_bar\`` > > > > > > I think it is wrong. It is not actively harmful unlike the the > > > combination of pci_iomap and then later use of accessors from the > > > ioremap family, but still not exactly a good idea. > > > > > > In a perfect world we'd have some different annotation from __iomem > > > for the whole iomap family of functions. > > > > So, what would be your suggestion for a) backportable change b) cleanup for > > the current and future drivers? > > Worry about getting it right first. Only after that should you even > consider stable tree backports. There's usually no reason you can't > just take the same change there as well. And if not, we will work > through it :) Okay, so if I read this thread correctly Christoph suggests to introduce pcim_ioremap_bar() and then use it. Am I right? Christoph, since we are on the topic about pcim_*() APIs, can you chime in the discussion [1] about IRQ vectors allocation? [1]: https://lore.kernel.org/all/20210607153916.1021016-1-zhengdejin5@xxxxxxxxx/ -- With Best Regards, Andy Shevchenko
