From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jagan Teki Subject: Re: [PATCH v2 5/9] drm/sun4i: tcon_top: Register clock gates in probe Date: Mon, 17 Jun 2019 15:59:50 +0530 Message-ID: References: <20190614164324.9427-1-jagan@amarulasolutions.com> <20190614164324.9427-6-jagan@amarulasolutions.com> Reply-To: jagan-dyjBcgdgk7Pe9wHmmfpqLFaTQe2KTcn/@public.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Return-path: Sender: linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org In-Reply-To: List-Post: , List-Help: , List-Archive: , List-Unsubscribe: , To: Chen-Yu Tsai Cc: Maxime Ripard , David Airlie , Daniel Vetter , dri-devel , linux-arm-kernel , linux-kernel , devicetree , Jernej Skrabec , Michael Trimarchi , linux-sunxi , linux-amarula List-Id: devicetree@vger.kernel.org On Sun, Jun 16, 2019 at 11:01 AM Chen-Yu Tsai wrote: > > On Sat, Jun 15, 2019 at 12:44 AM Jagan Teki wrote: > > > > TCON TOP have clock gates for TV0, TV1, dsi and right > > now these are register during bind call. > > > > Of which, dsi clock gate would required during DPHY probe > > but same can miss to get since tcon top is not bound at > > that time. > > > > To solve, this circular dependency move the clock gate > > registration from bind to probe so-that DPHY can get the > > dsi gate clock on time. > > > > Signed-off-by: Jagan Teki > > --- > > drivers/gpu/drm/sun4i/sun8i_tcon_top.c | 94 ++++++++++++++------------ > > 1 file changed, 49 insertions(+), 45 deletions(-) > > > > diff --git a/drivers/gpu/drm/sun4i/sun8i_tcon_top.c b/drivers/gpu/drm/sun4i/sun8i_tcon_top.c > > index 465e9b0cdfee..a8978b3fe851 100644 > > --- a/drivers/gpu/drm/sun4i/sun8i_tcon_top.c > > +++ b/drivers/gpu/drm/sun4i/sun8i_tcon_top.c > > @@ -124,7 +124,53 @@ static struct clk_hw *sun8i_tcon_top_register_gate(struct device *dev, > > static int sun8i_tcon_top_bind(struct device *dev, struct device *master, > > void *data) > > { > > - struct platform_device *pdev = to_platform_device(dev); > > + struct sun8i_tcon_top *tcon_top = dev_get_drvdata(dev); > > + int ret; > > + > > + ret = reset_control_deassert(tcon_top->rst); > > + if (ret) { > > + dev_err(dev, "Could not deassert ctrl reset control\n"); > > + return ret; > > + } > > + > > + ret = clk_prepare_enable(tcon_top->bus); > > + if (ret) { > > + dev_err(dev, "Could not enable bus clock\n"); > > + goto err_assert_reset; > > + } > > You have to de-assert the reset control and enable the clock before the > clocks it provides are registered. Otherwise a consumer may come in and > ask for the provided clock to be enabled, but since the TCON TOP's own > reset and clock are still disabled, you can't actually access the registers > that controls the provided clock. These rst and bus are common reset and bus clocks not tcon top clocks that are trying to register here. ie reason I have not moved it in top.