From: Maxime Ripard <mripard@kernel.org>
To: Jagan Teki <jagan@amarulasolutions.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
devicetree <devicetree@vger.kernel.org>,
Michael Trimarchi <michael@amarulasolutions.com>,
David Airlie <airlied@linux.ie>,
linux-kernel <linux-kernel@vger.kernel.org>,
dri-devel <dri-devel@lists.freedesktop.org>,
linux-sunxi <linux-sunxi@googlegroups.com>,
Rob Herring <robh+dt@kernel.org>, Chen-Yu Tsai <wens@csie.org>,
linux-amarula <linux-amarula@amarulasolutions.com>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
Icenowy Zheng <icenowy@aosc.io>
Subject: Re: [PATCH v11 4/7] drm/sun4i: dsi: Handle bus clock explicitly
Date: Sun, 3 Nov 2019 18:32:27 +0100 [thread overview]
Message-ID: <20191103173227.GF7001@gilmour> (raw)
In-Reply-To: <CAMty3ZAWPZSHtAZDf_0Dpx588YGGv3pJX1cXMfkZus3+WF94cA@mail.gmail.com>
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On Fri, Nov 01, 2019 at 07:42:55PM +0530, Jagan Teki wrote:
> Hi Maxime,
>
> On Tue, Oct 29, 2019 at 2:24 PM Maxime Ripard <mripard@kernel.org> wrote:
> >
> > On Tue, Oct 29, 2019 at 04:03:56AM +0530, Jagan Teki wrote:
> > > > > explicit handling of common clock would require since the A64
> > > > > doesn't need to mention the clock-names explicitly in dts since it
> > > > > support only one bus clock.
> > > > >
> > > > > Also pass clk_id NULL instead "bus" to regmap clock init function
> > > > > since the single clock variants no need to mention clock-names
> > > > > explicitly.
> > > >
> > > > You don't need explicit clock handling. Passing NULL as the argument
> > > > in regmap_init_mmio_clk will make it use the first clock, which is the
> > > > bus clock.
> > >
> > > Indeed I tried that, since NULL clk_id wouldn't enable the bus clock
> > > during regmap_mmio_gen_context code, passing NULL triggering vblank
> > > timeout.
> >
> > There's a bunch of users of NULL in tree, so finding out why NULL
> > doesn't work is the way forward.
>
> I'd have looked the some of the users before checking the code as
> well. As I said passing NULL clk_id to devm_regmap_init_mmio_clk =>
> __devm_regmap_init_mmio_clk would return before processing the clock.
>
> Here is the code snippet on the tree just to make sure I'm on the same
> page or not.
>
> static struct regmap_mmio_context *regmap_mmio_gen_context(struct device *dev,
> const char *clk_id,
> void __iomem *regs,
> const struct regmap_config *config)
> {
> -----------------------
> --------------
> if (clk_id == NULL)
> return ctx;
>
> ctx->clk = clk_get(dev, clk_id);
> if (IS_ERR(ctx->clk)) {
> ret = PTR_ERR(ctx->clk);
> goto err_free;
> }
>
> ret = clk_prepare(ctx->clk);
> if (ret < 0) {
> clk_put(ctx->clk);
> goto err_free;
> }
> -------------
> ---------------
> }
>
> Yes, I did check on the driver in the tree before committing explicit
> clock handle, which make similar requirements like us in [1]. this
> imx2 wdt driver is handling the explicit clock as well. I'm sure this
> driver is updated as I have seen few changes related to this driver in
> ML.
I guess we have two ways to go at this then.
Either we remove the return, but it might have a few side-effects, or
we call clk_get with NULL or bus depending on the case, and then call
regmap_mmio_attach_clk.
Maxime
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next prev parent reply other threads:[~2019-11-03 17:32 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-25 17:56 [PATCH v11 0/7] drm/sun4i: Allwinner A64 MIPI-DSI support Jagan Teki
2019-10-25 17:56 ` [PATCH v11 1/7] dt-bindings: sun6i-dsi: Document A64 MIPI-DSI controller Jagan Teki
2019-10-29 22:06 ` Rob Herring
2019-10-25 17:56 ` [PATCH v11 2/7] dt-bindings: sun6i-dsi: Add A64 DPHY compatible (w/ A31 fallback) Jagan Teki
2019-10-27 21:17 ` Rob Herring
2019-10-28 22:37 ` Jagan Teki
2019-10-25 17:56 ` [PATCH v11 3/7] drm/sun4i: dsi: Add has_mod_clk quirk Jagan Teki
2019-10-25 17:56 ` [PATCH v11 4/7] drm/sun4i: dsi: Handle bus clock explicitly Jagan Teki
2019-10-28 15:34 ` Maxime Ripard
2019-10-28 22:33 ` Jagan Teki
2019-10-29 8:54 ` Maxime Ripard
2019-11-01 14:12 ` Jagan Teki
2019-11-03 17:32 ` Maxime Ripard [this message]
2019-11-21 11:54 ` Jagan Teki
2019-11-22 18:18 ` Maxime Ripard
2019-11-22 19:50 ` Jagan Teki
2019-11-28 17:51 ` Maxime Ripard
2019-12-03 6:38 ` Jagan Teki
2019-10-25 17:56 ` [PATCH v11 5/7] drm/sun4i: dsi: Add Allwinner A64 MIPI DSI support Jagan Teki
2019-10-25 17:56 ` [PATCH v11 6/7] arm64: dts: allwinner: a64: Add MIPI DSI pipeline Jagan Teki
2019-10-25 17:56 ` [DO NOT MERGE] [PATCH v11 7/7] arm64: dts: allwinner: bananapi-m64: Enable Bananapi S070WV20-CT16 DSI panel Jagan Teki
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