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Message-ID: <CAMty3ZD5uxU=xb0z7PWaXzodYbWRJkP9HjGX-HZYFT4bwk0GOg@mail.gmail.com>
Date: Thu, 21 Nov 2019 17:24:47 +0530
From: Jagan Teki <jagan@...rulasolutions.com>
To: Maxime Ripard <mripard@...nel.org>
Cc: Mark Rutland <mark.rutland@....com>,
devicetree <devicetree@...r.kernel.org>,
David Airlie <airlied@...ux.ie>,
linux-sunxi <linux-sunxi@...glegroups.com>,
dri-devel <dri-devel@...ts.freedesktop.org>,
linux-kernel <linux-kernel@...r.kernel.org>,
Chen-Yu Tsai <wens@...e.org>, Rob Herring <robh+dt@...nel.org>,
Michael Trimarchi <michael@...rulasolutions.com>,
linux-amarula <linux-amarula@...rulasolutions.com>,
linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
Icenowy Zheng <icenowy@...c.io>
Subject: Re: [PATCH v11 4/7] drm/sun4i: dsi: Handle bus clock explicitly
Hi Maxime,
On Sun, Nov 3, 2019 at 11:02 PM Maxime Ripard <mripard@...nel.org> wrote:
>
> 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@...nel.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.
Thanks for the inputs.
Please have a look at this snippet, I have used your second
suggestions. let me know if you have any comments?
diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
index 8fa90cfc2ac8..91c95e56d870 100644
--- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
+++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
@@ -1109,24 +1109,36 @@ static int sun6i_dsi_probe(struct platform_device *pdev)
return PTR_ERR(dsi->regulator);
}
- dsi->regs = devm_regmap_init_mmio_clk(dev, "bus", base,
- &sun6i_dsi_regmap_config);
- if (IS_ERR(dsi->regs)) {
- dev_err(dev, "Couldn't create the DSI encoder regmap\n");
- return PTR_ERR(dsi->regs);
- }
-
dsi->reset = devm_reset_control_get_shared(dev, NULL);
if (IS_ERR(dsi->reset)) {
dev_err(dev, "Couldn't get our reset line\n");
return PTR_ERR(dsi->reset);
}
+ dsi->regs = regmap_init_mmio(dev, base, &sun6i_dsi_regmap_config);
+ if (IS_ERR(dsi->regs)) {
+ dev_err(dev, "Couldn't init regmap\n");
+ return PTR_ERR(dsi->regs);
+ }
+
+ dsi->bus_clk = devm_clk_get(dev, NULL);
+ if (IS_ERR(dsi->bus_clk)) {
+ dev_err(dev, "Couldn't get the DSI bus clock\n");
+ ret = PTR_ERR(dsi->bus_clk);
+ goto err_regmap;
+ } else {
+ printk("Jagan.. Got the BUS clock\n");
+ ret = regmap_mmio_attach_clk(dsi->regs, dsi->bus_clk);
+ if (ret)
+ goto err_bus_clk;
+ }
+
if (dsi->variant->has_mod_clk) {
dsi->mod_clk = devm_clk_get(dev, "mod");
if (IS_ERR(dsi->mod_clk)) {
dev_err(dev, "Couldn't get the DSI mod clock\n");
- return PTR_ERR(dsi->mod_clk);
+ ret = PTR_ERR(dsi->mod_clk);
+ goto err_attach_clk;
}
}
@@ -1167,6 +1179,14 @@ static int sun6i_dsi_probe(struct platform_device *pdev)
err_unprotect_clk:
if (dsi->variant->has_mod_clk)
clk_rate_exclusive_put(dsi->mod_clk);
+err_attach_clk:
+ if (!IS_ERR(dsi->bus_clk))
+ regmap_mmio_detach_clk(dsi->regs);
+err_bus_clk:
+ if (!IS_ERR(dsi->bus_clk))
+ clk_put(dsi->bus_clk);
+err_regmap:
+ regmap_exit(dsi->regs);
return ret;
}
@@ -1181,6 +1201,13 @@ static int sun6i_dsi_remove(struct platform_device *pdev)
if (dsi->variant->has_mod_clk)
clk_rate_exclusive_put(dsi->mod_clk);
+ if (!IS_ERR(dsi->bus_clk)) {
+ regmap_mmio_detach_clk(dsi->regs);
+ clk_put(dsi->bus_clk);
+ }
+
+ regmap_exit(dsi->regs);
+
return 0;
}
Jagan.
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