linux-kernel - Re: [PATCH 1/2] drm/i915/jsl: Split EHL/JSL platform info and PCI ids

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Date:   Mon, 28 Sep 2020 20:32:38 +0300
From:   Jani Nikula <jani.nikula@...ux.intel.com>
To:     Matt Roper <matthew.d.roper@...el.com>
Cc:     "Surendrakumar Upadhyay\, TejaskumarX" 
        <tejaskumarx.surendrakumar.upadhyay@...el.com>,
        "Vivi\, Rodrigo" <rodrigo.vivi@...el.com>,
        "airlied\@linux.ie" <airlied@...ux.ie>,
        "daniel\@ffwll.ch" <daniel@...ll.ch>,
        "intel-gfx\@lists.freedesktop.org" <intel-gfx@...ts.freedesktop.org>,
        "dri-devel\@lists.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "linux-kernel\@vger.kernel.org" <linux-kernel@...r.kernel.org>,
        "Ausmus\, James" <james.ausmus@...el.com>,
        "Souza\, Jose" <jose.souza@...el.com>,
        "ville.syrjala\@linux.intel.com" <ville.syrjala@...ux.intel.com>,
        "De Marchi\, Lucas" <lucas.demarchi@...el.com>,
        "Pandey\, Hariom" <hariom.pandey@...el.com>
Subject: Re: [PATCH 1/2] drm/i915/jsl: Split EHL/JSL platform info and PCI ids

On Mon, 28 Sep 2020, Matt Roper <matthew.d.roper@...el.com> wrote:
> Why are we adding IS_JASPERLAKE at all?  EHL/JSL are documented as the
> same graphics IP, but are paired with different PCHs in the final SoCs,
> which is what causes the minor differences in programming.  My
> understanding is that the voltage programming differences are ultimately
> due to that difference in PCH so we should just use HAS_PCH_MCC (EHL)
> and HAS_PCH_JSP (JSL) to distinguish which type of programming is needed
> rather than using a platform test.

Good point. If the difference is in the PCH, then of course the PCH
check should be used instead. Which avoids the problem altogether.

BR,
Jani.


-- 
Jani Nikula, Intel Open Source Graphics Center