Re: [PATCH v2 3/4] coresight: etm4x: Report the external outputs the PMU counts

[Leo Yan]

On Fri, Oct 23, 2026 at 10:49:40AM +0100, James Clark wrote:

[...]

> > >    * a device that matches one of its classes and has all of its capabilities.
> > >    */
> > >   #define CS_CFG_MATCH_CAP_MASK		0x0000ff00
> > > +/* trace unit external output n is countable by the PMU as TRCEXTOUTn */
> > > +#define CS_CFG_MATCH_CAP_PMU_EXTOUT_SHIFT	8
> > > +#define CS_CFG_MATCH_CAP_PMU_EXTOUT_NR	4	/* TRCEXTOUT0-3 */
> > > +#define CS_CFG_MATCH_CAP_PMU_EXTOUT(n)	BIT(CS_CFG_MATCH_CAP_PMU_EXTOUT_SHIFT + (n))
> 
> Isn't this recreating what GENMASK() and FIELD_PREP() does? Can we use that
> instead?

TBC, are you suggesting using separate capability bits to represent
TRCEXTOUT0-3? Why can't we use a single capability bit to indicate
whether the feature is supported and caps->num_event to indicate
the number of external output signals?