From: Boris Brezillon <boris.brezillon@free-electrons.com>
To: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>,
"Menon, Nishanth" <nm@ti.com>, Pawel Moll <pawel.moll@arm.com>,
Ian Campbell <ijc+devicetree@hellion.org.uk>,
David Airlie <airlied@linux.ie>,
Simon Hatliff <hatliff@cadence.com>,
Mark Rutland <mark.rutland@arm.com>,
dri-devel@lists.freedesktop.org,
Alan Douglas <adouglas@cadence.com>,
Rob Herring <robh+dt@kernel.org>, Jyri Sarha <jsarha@ti.com>,
Suresh Punnoose <sureshp@cadence.com>,
Kumar Gala <galak@codeaurora.org>,
Maxime Ripard <maxime.ripard@free-electrons.com>,
Richard Sproul <sproul@cadence.com>,
devicetree@vger.kernel.org
Subject: Re: [PATCH v5 1/2] drm/bridge: Add Cadence DSI driver
Date: Mon, 29 Jan 2018 15:16:21 +0100 [thread overview]
Message-ID: <20180129151621.546a9b8f@bbrezillon> (raw)
In-Reply-To: <07d82fcd-1e6c-37a8-36b7-d1a81cfeb2ae@ti.com>
On Mon, 29 Jan 2018 15:59:33 +0200
Tomi Valkeinen <tomi.valkeinen@ti.com> wrote:
> On 29/01/18 15:14, Boris Brezillon wrote:
>
> >> You don't disable the dsi_sys_clk neither in the ok nor in the error paths.
> >
> > Hm, it shouldn't be enabled in the first place: the runtime resume
> > hook takes care of enabling it, and we don't need this clock to access
> > IP registers (which is all we do in the probe).
>
> Ah, right, you can just use pm_runtime directly to enable the IP.
>
> I was looking at the docs, but it wasn't quite clear to me when exactly
> dsi_sys_clk is needed. I take it that you can access registers with just
> the dsi_p_clk, but you can't really do anything with the IP without
> dsi_sys_clk? If so, I think enabling both dsi_p_clk and dsi_sys_clk in
> the runtime PM callbacks is ok.
That's my understanding.
>
> Alternatively, if dsi_sys_clk is only needed for some specific
> functionality, a more correct way would be to enable that clock only
> when that operation is performed.
IIUC, it's needed to clock the PPI domain, so any operation
transmitting things on the DSI bus requires the sys clock.
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next prev parent reply other threads:[~2018-01-29 14:16 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-18 13:43 [PATCH v5 1/2] drm/bridge: Add Cadence DSI driver Boris Brezillon
[not found] ` <20180118134309.13123-1-boris.brezillon-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
2018-01-18 13:43 ` [PATCH v5 2/2] dt-bindings: drm/bridge: Document Cadence DSI bridge bindings Boris Brezillon
2018-01-29 11:56 ` [PATCH v5 1/2] drm/bridge: Add Cadence DSI driver Tomi Valkeinen
[not found] ` <9b45c6a3-f26b-59f5-d313-88290a2c5b42-l0cyMroinI0@public.gmane.org>
2018-01-29 13:14 ` Boris Brezillon
2018-01-29 13:46 ` Boris Brezillon
2018-01-29 13:59 ` Tomi Valkeinen
2018-01-29 14:16 ` Boris Brezillon [this message]
2018-01-29 13:16 ` Boris Brezillon
2018-01-29 14:29 ` Tomi Valkeinen
[not found] ` <47b5af31-4870-9109-291c-894455a1a15c-l0cyMroinI0@public.gmane.org>
2018-01-29 16:38 ` Boris Brezillon
2018-01-30 7:51 ` Tomi Valkeinen
[not found] ` <19cc13ff-d2eb-bc46-6ceb-c020ea3ddad3-l0cyMroinI0@public.gmane.org>
2018-01-30 8:17 ` Boris Brezillon
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