Subject: Re: linux-next: manual merge of the tip tree with the pm tree

From: Stephen Rothwell <[email-masked]>
Date: Thu, 29 May 2025 08:12:00 +1000

Hi Mario,

On Wed, 28 May 2025 14:14:40 +0000 "Limonciello, Mario" <[email-masked]> wrote:
>
> On 5/27/25 22:50, Stephen Rothwell wrote:
> > 
> > On Mon, 12 May 2025 15:23:26 +1000 Stephen Rothwell <[email-masked]> wrote:  
> >>
> >> On Mon, 12 May 2025 14:55:17 +1000 Stephen Rothwell <[email-masked]> wrote:  
> >>>
> >>> Today's linux-next merge of the tip tree got a conflict in:
> >>>
> >>>    drivers/cpufreq/amd-pstate.c
> >>>
> >>> between commit:
> >>>
> >>>    608a76b65288 ("cpufreq/amd-pstate: Add support for the "Requested CPU Min frequency" BIOS option")
> >>>
> >>> from the pm tree and commit:
> >>>
> >>>    d7484babd2c4 ("x86/msr: Rename 'rdmsrl_on_cpu()' to 'rdmsrq_on_cpu()'")
> >>>
> >>> from the tip tree.
> >>>
> >>> I fixed it up (the former removed a line updated by the latter) and can
> >>> carry the fix as necessary. This is now fixed as far as linux-next is
> >>> concerned, but any non trivial conflicts should be mentioned to your
> >>> upstream maintainer when your tree is submitted for merging.  You may
> >>> also want to consider cooperating with the maintainer of the conflicting
> >>> tree to minimise any particularly complex conflicts.  
> >>
> >> Actually it needed the fix up below.
> >>
> >>
> >> diff --cc drivers/cpufreq/amd-pstate.c
> >> index d96bb3e202ee,66fdc74f13ef..0d4c0de89a00
> >> --- a/drivers/cpufreq/amd-pstate.c
> >> +++ b/drivers/cpufreq/amd-pstate.c
> >> @@@ -389,10 -389,9 +389,10 @@@ static inline int amd_pstate_cppc_enabl
> >>    static int msr_init_perf(struct amd_cpudata *cpudata)
> >>    {
> >>    	union perf_cached perf = READ_ONCE(cpudata->perf);
> >>   -	u64 cap1, numerator;
> >>   +	u64 cap1, numerator, cppc_req;
> >>   +	u8 min_perf;
> >>    
> >> - 	int ret = rdmsrl_safe_on_cpu(cpudata->cpu, MSR_AMD_CPPC_CAP1,
> >> + 	int ret = rdmsrq_safe_on_cpu(cpudata->cpu, MSR_AMD_CPPC_CAP1,
> >>    				     &cap1);
> >>    	if (ret)
> >>    		return ret;
> >> @@@ -401,22 -400,6 +401,22 @@@
> >>    	if (ret)
> >>    		return ret;
> >>    
> >> - 	ret = rdmsrl_on_cpu(cpudata->cpu, MSR_AMD_CPPC_REQ, &cppc_req);
> >> ++	ret = rdmsrq_on_cpu(cpudata->cpu, MSR_AMD_CPPC_REQ, &cppc_req);
> >>   +	if (ret)
> >>   +		return ret;
> >>   +
> >>   +	WRITE_ONCE(cpudata->cppc_req_cached, cppc_req);
> >>   +	min_perf = FIELD_GET(AMD_CPPC_MIN_PERF_MASK, cppc_req);
> >>   +
> >>   +	/*
> >>   +	 * Clear out the min_perf part to check if the rest of the MSR is 0, if yes, this is an
> >>   +	 * indication that the min_perf value is the one specified through the BIOS option
> >>   +	 */
> >>   +	cppc_req &= ~(AMD_CPPC_MIN_PERF_MASK);
> >>   +
> >>   +	if (!cppc_req)
> >>   +		perf.bios_min_perf = min_perf;
> >>   +
> >>    	perf.highest_perf = numerator;
> >>    	perf.max_limit_perf = numerator;
> >>    	perf.min_limit_perf = FIELD_GET(AMD_CPPC_LOWEST_PERF_MASK, cap1);  
> > 
> > This is now a conflict between the pm tree and Linus' tree.
> >   
> 
> I thought that Ingo added an extra #define for compatibility?

Having that define does not change the above conflict at all.  It just
means that further additions of calls to rdmsrl_safe_on_cpu() will not
cause build failures.

-- 
Cheers,
Stephen Rothwell