On Wed, Jun 10, 2026 at 05:40:56PM +0300, Svyatoslav Ryhel wrote: > вт, 9 черв. 2026 р. о 22:17 Andy Shevchenko <[email protected]> > пише: > > On Sat, Jun 06, 2026 at 07:57:34AM +0300, Svyatoslav Ryhel wrote: > > > Missing coherent_dma_mask assigning triggers the following warning in > > > dmesg: > > > > > > [ 3.287872] platform lm3533-backlight.0: DMA mask not set > > > > > > Since this warning might be elevated to an error in the future, set > > > coherent_dma_mask to zero because both the core and cells do not utilize > > > DMA. > > > > Hmm... I am not sure about this. The entire kernel has only two drivers that > > do that, and thanks to their commit messages one of them pointed out to the > > commit from 2018. So, if no other devices suffer from this, I think it has > > to > > be a better way of achieving the same. > > If mfd framework warns that DMA mask is not set then this must be > addressed. Why then there is such warning at the first place if mask > can be just skipped. Then warning would be just a debug message. What > is warning today can become error tomorrow.
It's there for 8 years. And only a few drivers explicitly nullify it. I think doing this patch one should really understand what's going on. (Note, I'm not that person, it's my gut feelings based on the experience and the above statistics.) MFD creates a lot of platform devices for which DMA mask is set automatically. So, why is it not set properly for this device? -- With Best Regards, Andy Shevchenko
