Re: [PATCHv2 2/3] ARM: drm: Intel FPGA VIP Frame Buffer II drm driver

["Ong, Hean Loong" <hean.loong.ong-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>]

On Wed, 2017-05-03 at 13:34 -0700, Eric Anholt wrote:
> hean.loong.ong@intel.com writes:
> 
> > 
> > From: "Ong, Hean Loong" <hean.loong.ong@intel.com>
> > 
> > Driver for Intel FPGA Video and Image Processing
> > Suite Frame Buffer II. The driver only supports the Intel
> > Arria10 devkit and its variants. This driver can be either
> > loaded staticlly or in modules. The OF device tree binding
> > is located at:
> > Documentation/devicetree/bindings/display/altr,vip-fb2.txt
> > 
> > Signed-off-by: Ong, Hean Loong <hean.loong.ong@intel.com>
> I'm not sure if this driver is going to make sense as-is, if it
> doesn't
> actually do display of planes from system memory.  But in case I was
> wrong, here's my review:
> 
> 
> > 
> > diff --git a/drivers/gpu/drm/ivip/intel_vip_conn.c
> > b/drivers/gpu/drm/ivip/intel_vip_conn.c
> > new file mode 100644
> > index 0000000..499d3b4
> > --- /dev/null
> > +++ b/drivers/gpu/drm/ivip/intel_vip_conn.c
> > @@ -0,0 +1,96 @@
> > +/*
> > + * intel_vip_conn.c -- Intel Video and Image Processing(VIP)
> > + * Frame Buffer II driver
> > + *
> > + * This driver supports the Intel VIP Frame Reader component.
> > + * More info on the hardware can be found in the Intel Video
> > + * and Image Processing Suite User Guide at this address
> > + * http://www.altera.com/literature/ug/ug_vip.pdf.
> > + *
> > + * This program is free software; you can redistribute it and/or
> > modify it
> > + * under the terms and conditions of the GNU General Public
> > License,
> > + * version 2, as published by the Free Software Foundation.
> > + *
> > + * This program is distributed in the hope it will be useful, but
> > WITHOUT
> > + * ANY WARRANTY; without even the implied warranty of
> > MERCHANTABILITY or
> > + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
> > License for
> > + * more details.
> > + *
> > + * Authors:
> > + * Ong, Hean-Loong <hean.loong.ong@intel.com>
> > + *
> > + */
> > +
> > +#include <linux/init.h>
> > +#include <linux/kernel.h>
> > +#include <drm/drm_atomic_helper.h>
> > +#include <drm/drm_crtc_helper.h>
> > +#include <drm/drm_encoder_slave.h>
> > +#include <drm/drm_plane_helper.h>
> > +
> > +static enum drm_connector_status
> > +intelvipfb_drm_connector_detect(struct drm_connector *connector,
> > bool force)
> > +{
> > +	return connector_status_connected;
> > +}
> > +
> > +static void intelvipfb_drm_connector_destroy(struct drm_connector
> > *connector)
> > +{
> > +	drm_connector_unregister(connector);
> > +	drm_connector_cleanup(connector);
> > +}
> > +
> > +static const struct drm_connector_funcs
> > intelvipfb_drm_connector_funcs = {
> > +	.dpms = drm_helper_connector_dpms,
> > +	.reset = drm_atomic_helper_connector_reset,
> > +	.detect = intelvipfb_drm_connector_detect,
> > +	.fill_modes = drm_helper_probe_single_connector_modes,
> > +	.destroy = intelvipfb_drm_connector_destroy,
> > +	.atomic_duplicate_state =
> > drm_atomic_helper_connector_duplicate_state,
> > +	.atomic_destroy_state =
> > drm_atomic_helper_connector_destroy_state,
> > +};
> > +
> > +static int intelvipfb_drm_connector_get_modes(struct drm_connector
> > *connector)
> > +{
> > +	struct drm_device *drm = connector->dev;
> > +	int count;
> > +
> > +	count = drm_add_modes_noedid(connector, drm-
> > >mode_config.max_width,
> > +				     drm->mode_config.max_height);
> > +	drm_set_preferred_mode(connector, drm-
> > >mode_config.max_width,
> > +			       drm->mode_config.max_height);
> > +	return count;
> > +}
> You're adding a bunch of modes here, but I don't see anywhere in the
> driver that you change the resolution being scanned out.
> 
> If you can't change resolution, then I'd probably use drm_gtf_mode()
> or
> something to generate just the one mode (do you have a vrefresh for
> it?).  Also, in the simple display pipe's atomic_check, make sure
> that
> the mode chosen is the width/height you can support.
> 
From the drivers perpective the resolution is dependant on how the FPGA
Display Port Framebuffer hardwware IP is designed. I would take a look
into how drm_gtf_mode() works compared to this.
> > 
> > +
> > +static const struct drm_connector_helper_funcs
> > +intelvipfb_drm_connector_helper_funcs = {
> > +	.get_modes = intelvipfb_drm_connector_get_modes,
> > +};
> > +
> > +struct drm_connector *
> > +intelvipfb_conn_setup(struct drm_device *drm)
> > +{
> > +	struct drm_connector *conn;
> > +	int ret;
> > +
> > +	conn = devm_kzalloc(drm->dev, sizeof(*conn), GFP_KERNEL);
> > +	if (IS_ERR(conn))
> > +		return NULL;
> > +
> > +	ret = drm_connector_init(drm, conn,
> > &intelvipfb_drm_connector_funcs,
> > +				 DRM_MODE_CONNECTOR_DisplayPort);
> Are you actually outputting DisplayPort
> (https://en.wikipedia.org/wiki/DisplayPort)?
> 
> You probably want something else from the DRM_MODE_CONNECTOR list, or
> maybe just DRM_MODE_CONNECTOR_Unknown.
> 
The Physical Connector is a Display Port connector. A simple
introduction of the product is found here.
https://www.altera.com/content/dam/altera-www/global/en_US/pdfs/literat
ure/an/an793.pdf
> 
> > 
> > +	if (ret < 0) {
> > +		dev_err(drm->dev, "failed to initialize drm
> > connector\n");
> > +		ret = -ENOMEM;
> > +		goto error_connector_cleanup;
> > +	}
> > +
> > +	drm_connector_helper_add(conn,
> > &intelvipfb_drm_connector_helper_funcs);
> > +
> > +	return conn;
> > +
> > +error_connector_cleanup:
> > +	drm_connector_cleanup(conn);
> > +
> > +	return NULL;
> > +}
> > diff --git a/drivers/gpu/drm/ivip/intel_vip_core.c
> > b/drivers/gpu/drm/ivip/intel_vip_core.c
> > new file mode 100644
> > index 0000000..4e83343
> > --- /dev/null
> > +++ b/drivers/gpu/drm/ivip/intel_vip_core.c
> > @@ -0,0 +1,171 @@
> > +/*
> > + * intel_vip_core.c -- Intel Video and Image Processing(VIP)
> > + * Frame Buffer II driver
> > + *
> > + * This driver supports the Intel VIP Frame Reader component.
> > + * More info on the hardware can be found in the Intel Video
> > + * and Image Processing Suite User Guide at this address
> > + * http://www.altera.com/literature/ug/ug_vip.pdf.
> > + *
> > + * This program is free software; you can redistribute it and/or
> > modify it
> > + * under the terms and conditions of the GNU General Public
> > License,
> > + * version 2, as published by the Free Software Foundation.
> > + *
> > + * This program is distributed in the hope it will be useful, but
> > WITHOUT
> > + * ANY WARRANTY; without even the implied warranty of
> > MERCHANTABILITY or
> > + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
> > License for
> > + * more details.
> > + *
> > + * Authors:
> > + * Ong, Hean-Loong <hean.loong.ong@intel.com>
> > + *
> > + */
> > +
> > +#include <linux/init.h>
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +
> > +#include <drm/drmP.h>
> > +#include <drm/drm_atomic.h>
> > +#include <drm/drm_atomic_helper.h>
> > +#include <drm/drm_crtc_helper.h>
> > +#include <drm/drm_fb_helper.h>
> > +#include <drm/drm_fb_cma_helper.h>
> > +#include <drm/drm_gem_cma_helper.h>
> > +#include <drm/drm_plane_helper.h>
> > +#include <drm/drm_simple_kms_helper.h>
> > +
> > +#include "intel_vip_drv.h"
> > +
> > +static const u32 fbpriv_formats[] = {
> > +	DRM_FORMAT_XRGB8888,
> > +	DRM_FORMAT_RGB565
> > +};
> You're registering that you support this set of formats, but I don't
> see
> anything programming the hardware differently based on the format of
> the
> plane.
> 
> > 
> > +static void intelvipfb_start_hw(void __iomem *base,
> > resource_size_t addr)
> > +{
> > +	/*
> > +	 * The frameinfo variable has to correspond to the size of
> > the VIP Suite
> > +	 * Frame Reader register 7 which will determine the
> > maximum size used
> > +	 * in this frameinfo
> > +	 */
> > +
> > +	u32 frameinfo;
> > +
> > +	frameinfo =
> > +		readl(base + INTELVIPFB_FRAME_READER) &
> > 0x00ffffff;
> > +	writel(frameinfo, base + INTELVIPFB_FRAME_INFO);
> > +	writel(addr, base + INTELVIPFB_FRAME_START);
> > +	/* Finally set the control register to 1 to start
> > streaming */
> > +	writel(1, base + INTELVIPFB_CONTROL);
> > +}
> The addr you're passing in here is from dev->mode_config.fb_base,
> which
> is this weird sideband value from drm_fbdev_cma.  It's the wrong
> value
> to use if anything else uses the KMS interfaces to change the plane
> --
> you should be using
> drm_fb_cma_get_gem_addr(drm_simple_display_pipe->plane->state, 0)
> instead.
> 
Thank you for highlighting this. Will look into using
drm_fb_cma_get_gem_addr(drm_simple_display_pipe->plane->state, 0)
> > 
> > +
> > +static void intelvipfb_disable_hw(void __iomem *base)
> > +{
> > +	/* set the control register to 0 to stop streaming */
> > +	writel(0, base + INTELVIPFB_CONTROL);
> > +}
> These two functions should be be called from fbpriv_funcs.enable()
> and
> .disable(), not device load/unload.
> 
Since I am not supporting hotplugging here would it make a difference?
>  
> > 
> > +static const struct drm_mode_config_funcs
> > intelvipfb_mode_config_funcs = {
> > +	.fb_create = drm_fb_cma_create,
> > +	.atomic_check = drm_atomic_helper_check,
> > +	.atomic_commit = drm_atomic_helper_commit,
> > +};
> > +
> > +static struct drm_mode_config_helper_funcs
> > intelvipfb_mode_config_helpers = {
> > +	.atomic_commit_tail = drm_atomic_helper_commit_tail,
> > +};
> > +
> > +static void intelvipfb_setup_mode_config(struct drm_device *drm)
> > +{
> > +	drm_mode_config_init(drm);
> > +	drm->mode_config.funcs = &intelvipfb_mode_config_funcs;
> > +	drm->mode_config.helper_private =
> > &intelvipfb_mode_config_helpers;
> > +}
> > +
> > +static int intelvipfb_pipe_prepare_fb(struct
> > drm_simple_display_pipe *pipe,
> > +				      struct drm_plane_state
> > *plane_state)
> > +{
> > +	return drm_fb_cma_prepare_fb(&pipe->plane, plane_state);
> > +}
> > +
> > +static struct drm_simple_display_pipe_funcs fbpriv_funcs = {
> > +	.prepare_fb = intelvipfb_pipe_prepare_fb,
> > +};
> > +
> > +int intelvipfb_probe(struct device *dev, void __iomem *base)
> > +{
> > +	int retval;
> > +	struct drm_device *drm;
> > +	struct intelvipfb_priv *fbpriv = dev_get_drvdata(dev);
> > +	struct drm_connector *connector;
> > +
> > +	dev_set_drvdata(dev, fbpriv);
> > +
> > +	drm = fbpriv->drm;
> > +
> > +	intelvipfb_setup_mode_config(drm);
> > +
> > +	connector = intelvipfb_conn_setup(drm);
> > +	if (!connector) {
> > +		dev_err(drm->dev, "Connector setup failed\n");
> > +		goto err_mode_config;
> > +	}
> > +
> > +	retval = drm_simple_display_pipe_init(drm, &fbpriv->pipe,
> > +					      &fbpriv_funcs,
> > +					      fbpriv_formats,
> > +					      ARRAY_SIZE(fbpriv_fo
> > rmats),
> > +					      connector);
> > +	if (retval < 0) {
> > +		dev_err(drm->dev, "Cannot setup simple display
> > pipe\n");
> > +		goto err_mode_config;
> > +	}
> > +
> > +	fbpriv->fbcma = drm_fbdev_cma_init(drm, PREF_BPP,
> > +					   drm-
> > >mode_config.num_connector);
> > +	if (!fbpriv->fbcma) {
> > +		fbpriv->fbcma = NULL;
> > +		dev_err(drm->dev, "Failed to init FB CMA area\n");
> > +		goto err_mode_config;
> > +	}
> On failure, drm_fbdev_cma_init() returns an ERR_PTR, not NULL.
> 
> Also, you're passing this PREF_BPP value here, ignoring
> the altr,bits-per-symbol property.  That seems wrong.

Noted thanks for highlighting.