linux-kernel - Re: [PATCH v2 04/15] drm/mxsfb: Reset vital register for a proper initialization

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Message-ID: <18d5f58deba8044042ab7b8d98a72803@agner.ch>
Date:   Wed, 14 Aug 2019 13:11:03 +0200
From:   Stefan Agner <stefan@...er.ch>
To:     Robert Chiras <robert.chiras@....com>
Cc:     Guido Günther <agx@...xcpu.org>,
        Marek Vasut <marex@...x.de>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        NXP Linux Team <linux-imx@....com>,
        dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 04/15] drm/mxsfb: Reset vital register for a proper
 initialization

On 2019-08-14 12:48, Robert Chiras wrote:
> Some of the regiters need, like LCDC_CTRL and CTRL2_OUTSTANDING_REQS

Typo in registers, and there is a need to many.

> needs to be properly cleared and initialized for a better start and stop
> routine.



> 
> Signed-off-by: Robert Chiras <robert.chiras@....com>
> ---
>  drivers/gpu/drm/mxsfb/mxsfb_crtc.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
> b/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
> index b69ace8..5e44f57 100644
> --- a/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
> +++ b/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
> @@ -127,6 +127,10 @@ static void mxsfb_enable_controller(struct
> mxsfb_drm_private *mxsfb)
>  		clk_prepare_enable(mxsfb->clk_disp_axi);
>  	clk_prepare_enable(mxsfb->clk);
>  
> +	if (mxsfb->devdata->ipversion >= 4)
> +		writel(CTRL2_OUTSTANDING_REQS(REQ_16),
> +		       mxsfb->base + LCDC_V4_CTRL2 + REG_SET);
> +
>  	/* If it was disabled, re-enable the mode again */
>  	writel(CTRL_DOTCLK_MODE, mxsfb->base + LCDC_CTRL + REG_SET);
>  
> @@ -136,12 +140,19 @@ static void mxsfb_enable_controller(struct
> mxsfb_drm_private *mxsfb)
>  	writel(reg, mxsfb->base + LCDC_VDCTRL4);
>  
>  	writel(CTRL_RUN, mxsfb->base + LCDC_CTRL + REG_SET);
> +	writel(CTRL1_RECOVERY_ON_UNDERFLOW, mxsfb->base + LCDC_CTRL1 + REG_SET);

This seems not to be accounted for in the commit message. Can you do
this in a separate commit?

Also I suggest to introduce CTRL1_RECOVERY_ON_UNDERFLOW in that same
commit.

--
Stefan

>  }
>  
>  static void mxsfb_disable_controller(struct mxsfb_drm_private *mxsfb)
>  {
>  	u32 reg;
>  
> +	if (mxsfb->devdata->ipversion >= 4)
> +		writel(CTRL2_OUTSTANDING_REQS(0x7),
> +		       mxsfb->base + LCDC_V4_CTRL2 + REG_CLR);
> +
> +	writel(CTRL_RUN, mxsfb->base + LCDC_CTRL + REG_CLR);
> +
>  	/*
>  	 * Even if we disable the controller here, it will still continue
>  	 * until its FIFOs are running out of data
> @@ -295,6 +306,7 @@ void mxsfb_crtc_enable(struct mxsfb_drm_private *mxsfb)
>  	dma_addr_t paddr;
>  
>  	mxsfb_enable_axi_clk(mxsfb);
> +	writel(0, mxsfb->base + LCDC_CTRL);
>  	mxsfb_crtc_mode_set_nofb(mxsfb);
>  
>  	/* Write cur_buf as well to avoid an initial corrupt frame */