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Date:   Fri, 7 Jun 2019 14:49:49 +0300
From:   Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To:     Jacopo Mondi <jacopo+renesas@jmondi.org>
Cc:     kieran.bingham+renesas@ideasonboard.com, airlied@linux.ie,
        daniel@ffwll.ch, koji.matsuoka.xm@renesas.com, muroya@ksk.co.jp,
        VenkataRajesh.Kalakodima@in.bosch.com,
        Harsha.ManjulaMallikarjun@in.bosch.com,
        linux-renesas-soc@vger.kernel.org, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 16/20] drm: rcar-du: kms: Collect CMM instances
Message-ID: <20190607114949.GE7593@pendragon.ideasonboard.com>
References: <20190606142220.1392-1-jacopo+renesas@jmondi.org>
 <20190606142220.1392-17-jacopo+renesas@jmondi.org>
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In-Reply-To: <20190606142220.1392-17-jacopo+renesas@jmondi.org>
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Hi Jacopo,

Thank you for the patch.

On Thu, Jun 06, 2019 at 04:22:16PM +0200, Jacopo Mondi wrote:
> Implement device tree parsing to collect the available CMM instances
> described by the 'cmms' property. Associate CMMs with CRTCs and store a
> mask of active CMMs in the DU group for later enablement.
> 
> Also define a new feature to let each SoC claim support for CMM.

The feature is added in the previous patch.

> Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> ---
>  drivers/gpu/drm/rcar-du/rcar_du_crtc.c  |  7 ++++
>  drivers/gpu/drm/rcar-du/rcar_du_crtc.h  |  2 +
>  drivers/gpu/drm/rcar-du/rcar_du_drv.h   |  3 ++
>  drivers/gpu/drm/rcar-du/rcar_du_group.h |  2 +
>  drivers/gpu/drm/rcar-du/rcar_du_kms.c   | 50 +++++++++++++++++++++++++
>  5 files changed, 64 insertions(+)
> 
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
> index 2da46e3dc4ae..9f270a54b164 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
> @@ -1194,6 +1194,13 @@ int rcar_du_crtc_create(struct rcar_du_group *rgrp, unsigned int swindex,
>  	if (ret < 0)
>  		return ret;
>  
> +	/* CMM might be disabled for this CRTC. */
> +	if (rcar_du_has(rcdu, RCAR_DU_FEATURE_CMM) &&
> +	    rcdu->cmms[swindex]) {

You can skip testing RCAR_DU_FEATURE_CMM here as rcdu->cmms[swindex]
can't be set if the feature isn't available.

> +		rcrtc->cmm = rcdu->cmms[swindex];
> +		rgrp->cmms_mask |= BIT(hwindex % 2);
> +	}
> +
>  	drm_crtc_helper_add(crtc, &crtc_helper_funcs);
>  
>  	/* Start with vertical blanking interrupt reporting disabled. */
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_crtc.h b/drivers/gpu/drm/rcar-du/rcar_du_crtc.h
> index 3b7fc668996f..5f2940c42225 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_crtc.h
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_crtc.h
> @@ -39,6 +39,7 @@ struct rcar_du_vsp;
>   * @vblank_wait: wait queue used to signal vertical blanking
>   * @vblank_count: number of vertical blanking interrupts to wait for
>   * @group: CRTC group this CRTC belongs to
> + * @cmm: CMM associated with this CRTC
>   * @vsp: VSP feeding video to this CRTC
>   * @vsp_pipe: index of the VSP pipeline feeding video to this CRTC
>   * @writeback: the writeback connector
> @@ -64,6 +65,7 @@ struct rcar_du_crtc {
>  	unsigned int vblank_count;
>  
>  	struct rcar_du_group *group;
> +	struct platform_device *cmm;
>  	struct rcar_du_vsp *vsp;
>  	unsigned int vsp_pipe;
>  
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_drv.h b/drivers/gpu/drm/rcar-du/rcar_du_drv.h
> index a00dccc447aa..300ec60ba31b 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_drv.h
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_drv.h
> @@ -13,6 +13,7 @@
>  #include <linux/kernel.h>
>  #include <linux/wait.h>
>  
> +#include "rcar_cmm.h"
>  #include "rcar_du_crtc.h"
>  #include "rcar_du_group.h"
>  #include "rcar_du_vsp.h"
> @@ -70,6 +71,7 @@ struct rcar_du_device_info {
>  
>  #define RCAR_DU_MAX_CRTCS		4
>  #define RCAR_DU_MAX_GROUPS		DIV_ROUND_UP(RCAR_DU_MAX_CRTCS, 2)
> +#define RCAR_DU_MAX_CMMS		4
>  #define RCAR_DU_MAX_VSPS		4
>  
>  struct rcar_du_device {
> @@ -86,6 +88,7 @@ struct rcar_du_device {
>  	struct rcar_du_encoder *encoders[RCAR_DU_OUTPUT_MAX];
>  
>  	struct rcar_du_group groups[RCAR_DU_MAX_GROUPS];
> +	struct platform_device *cmms[RCAR_DU_MAX_CMMS];
>  	struct rcar_du_vsp vsps[RCAR_DU_MAX_VSPS];
>  
>  	struct {
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_group.h b/drivers/gpu/drm/rcar-du/rcar_du_group.h
> index 87950c1f6a52..b0c1466593a3 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_group.h
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_group.h
> @@ -22,6 +22,7 @@ struct rcar_du_device;
>   * @mmio_offset: registers offset in the device memory map
>   * @index: group index
>   * @channels_mask: bitmask of populated DU channels in this group
> + * @cmms_mask: bitmask of enabled CMMs in this group
>   * @num_crtcs: number of CRTCs in this group (1 or 2)
>   * @use_count: number of users of the group (rcar_du_group_(get|put))
>   * @used_crtcs: number of CRTCs currently in use
> @@ -37,6 +38,7 @@ struct rcar_du_group {
>  	unsigned int index;
>  
>  	unsigned int channels_mask;
> +	unsigned int cmms_mask;
>  	unsigned int num_crtcs;
>  	unsigned int use_count;
>  	unsigned int used_crtcs;
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_kms.c b/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> index adbc4f5d8fc5..5a910a04e1d9 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> @@ -18,6 +18,7 @@
>  #include <drm/drm_vblank.h>
>  
>  #include <linux/of_graph.h>
> +#include <linux/of_platform.h>
>  #include <linux/wait.h>
>  
>  #include "rcar_du_crtc.h"
> @@ -614,6 +615,48 @@ static int rcar_du_vsps_init(struct rcar_du_device *rcdu)
>  	return ret;
>  }
>  
> +static int rcar_du_cmm_init(struct rcar_du_device *rcdu)
> +{
> +	const struct device_node *np = rcdu->dev->of_node;
> +	unsigned int cells;
> +	unsigned int i;
> +
> +	cells = of_property_count_u32_elems(np, "cmms");
> +	if (cells > RCAR_DU_MAX_CMMS || cells > rcdu->num_crtcs) {
> +		dev_err(rcdu->dev, "invalid 'cmms' property format\n");
> +		return -EINVAL;
> +	}

I don't think you need to count the elements first, you can loop over
the number of CRTCs below.

> +
> +	for (i = 0; i < cells; ++i) {
> +		struct platform_device *pdev;
> +		struct device_node *cmm;
> +
> +		cmm = of_parse_phandle(np, "cmms", i);
> +		if (IS_ERR(cmm)) {
> +			dev_err(rcdu->dev, "failed to parse 'cmms' property\n");
> +			return PTR_ERR(cmm);
> +		}
> +
> +		pdev = of_find_device_by_node(cmm);
> +		if (IS_ERR(pdev)) {
> +			dev_err(rcdu->dev, "invalid property 'cmms'[%u]\n", i);

How about "No device found for cmms[%u]\n" ?

> +			of_node_put(cmm);
> +			return PTR_ERR(pdev);
> +		}
> +
> +		if (!of_device_is_available(cmm)) {
> +			/* It's fine to have a phandle to a non-enabled CMM. */
> +			of_node_put(cmm);
> +			continue;
> +		}
> +
> +		of_node_put(cmm);
> +		rcdu->cmms[i] = pdev;
> +	}
> +
> +	return 0;
> +}
> +
>  int rcar_du_modeset_init(struct rcar_du_device *rcdu)
>  {
>  	static const unsigned int mmio_offsets[] = {
> @@ -704,6 +747,13 @@ int rcar_du_modeset_init(struct rcar_du_device *rcdu)
>  			return ret;
>  	}
>  
> +	/* Initialize the Color Management Modules. */
> +	if (rcar_du_has(rcdu, RCAR_DU_FEATURE_CMM)) {

Instead of using a feature, could we simply return 0 in
rcar_du_cmm_init() if the cmms property doesn't exist ? This will
preserve compatibility with older DTs.

> +		ret = rcar_du_cmm_init(rcdu);
> +		if (ret < 0)
> +			return ret;
> +	}
> +
>  	/* Create the CRTCs. */
>  	for (swindex = 0, hwindex = 0; swindex < rcdu->num_crtcs; ++hwindex) {
>  		struct rcar_du_group *rgrp;

-- 
Regards,

Laurent Pinchart