[Intel-gfx] [PATCH v2] drm/i915/display: Use unions per platform in intel_dpll_hw_state

[Souza, Jose]

On Thu, 2022-02-24 at 15:25 +0200, Ville Syrjälä wrote:
> On Thu, Feb 24, 2022 at 01:17:35PM +0000, Souza, Jose wrote:
> > On Thu, 2022-02-24 at 12:20 +0200, Ville Syrjälä wrote:
> > > On Wed, Feb 23, 2022 at 12:55:51PM -0800, José Roberto de Souza wrote:
> > > <snip>
> > > > +	union {
> > > > +		/* icl+ TC */
> > > > +		struct {
> > > > +			u32 mg_refclkin_ctl;
> > > > +			u32 mg_clktop2_coreclkctl1;
> > > > +			u32 mg_clktop2_hsclkctl;
> > > > +			u32 mg_pll_div0;
> > > > +			u32 mg_pll_div1;
> > > > +			u32 mg_pll_lf;
> > > > +			u32 mg_pll_frac_lock;
> > > > +			u32 mg_pll_ssc;
> > > > +			u32 mg_pll_bias;
> > > > +			u32 mg_pll_tdc_coldst_bias;
> > > > +			u32 mg_pll_bias_mask;
> > > > +			u32 mg_pll_tdc_coldst_bias_mask;
> > > > +		};
> > > > +
> > > > +		/* bxt */
> > > > +		struct {
> > > > +			/* bxt */
> > > > +			u32 ebb0;
> > > > +			u32 ebb4;
> > > > +			u32 pll0;
> > > > +			u32 pll1;
> > > > +			u32 pll2;
> > > > +			u32 pll3;
> > > > +			u32 pll6;
> > > > +			u32 pll8;
> > > > +			u32 pll9;
> > > > +			u32 pll10;
> > > > +			u32 pcsdw12;
> > > > +		};
> > > 
> > > Wasn't there some funny compiler bug around anonymous unions?
> > > git log --grep='anon.*union' seems to agree. Please double check
> > > that stuff to make sure this is actually safe.
> > 
> > I don't see any patch referring to compiler issues with 'git log --grep='anon.*union', what I see is other subsystems making use of it too.
> > Can you share the commit hash that you are referring to?
> 
> $ git log --format=oneline --grep='anon.*union' -- drivers/gpu/drm/i915
> 

I see issues with initialization of anonymous union but we don't initialize intel_dpll_hw_state.
Also it was fixed on GCC 4.6 that is older than current GCC requirement to build kernel(GCC 5.1).

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=10676