Re: [PATCH 6.9 1/2] wifi: iwlwifi: mvm: support iwl_dev_tx_power_cmd_v8

["gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>]

On Wed, Jun 19, 2024 at 09:03:34AM +0000, Grumbach, Emmanuel wrote:
> On Wed, 2024-06-19 at 10:51 +0200, Greg KH wrote:
> > On Tue, Jun 18, 2024 at 02:09:23PM +0300, Emmanuel Grumbach wrote:
> > > commit 8f892e225f416fcf2b55a0f9161162e08e2b0cc7 upstream.
> > > 
> > > This just adds a __le32 that we (currently) don't use.
> > 
> > Why is this needed for a stable tree if this is nothing that is actually
> > used and then we need another fix for it after that?
> 
> Right, so I totally understand you're confused... I should probably have re-written the commit
> message to explain why this is needed for stable...
> 
> This patch allows to handle a new version of a specific command to the firmware. As explained in the
> commit message, we don't need the new field, but ... the command got bigger and we must align to the
> new size of course. If we don't, the firmware will get a command that is shorter than expected and
> will crash.
> We originally didn't think we'd need that on the firmware versions supported by kernel 6.9 and this
> is why we didn't queue this patch for 6.9. Now, it appears that the latest firmware version that 6.9
> supports does need the new version of the command.
> Unfortunately, we learnt that the hard way, through bugzilla :-(
> 
> Now, this patch introduced a regression that is fixed by another patch...
> Would you prefer me to squash them?
> 
> > 
> > I can't see how this commit actually does anything on it's own, what am
> > I missing?
> > 
> > What bug is this fixing?  A regression?  Is this a new feature?
> 
> So, yes, it fixes a bug as explained above.
> This is a regression because older kernels won't load the new firmware and won't hit the firmware
> crash.
> 
> > 
> > confused,
> 
> I should have re-written the commit message. Sorry.
> I hope things are now clearer..

Keeping the commit message the same is fine, and not squashing is also
fine, but a huge hint as to _why_ this is relevent for the stable trees
would have been appreciated.  That's what [0/X] email blurbs are for :)

thanks, I'll go queue these up now.

greg k-h