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Date:	Wed, 6 Jul 2011 11:39:38 -0400
From:	Alex Deucher <alexdeucher@...il.com>
To:	reimth@...glemail.com
Cc:	Dave Airlie <airlied@...hat.com>,
	Mario Kleiner <mario.kleiner@...bingen.mpg.de>,
	Jean Delvare <khali@...ux-fr.org>,
	Tyson Whitehead <twhitehead@...il.com>,
	Jason Wessel <jason.wessel@...driver.com>,
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	Thomas Reim <rdratlos@...oo.co.uk>
Subject: Re: [PATCH] drm/radeon: Fix Asus M2A-VM HDMI EDID error flooding problem

On Wed, Jul 6, 2011 at 6:09 AM,  <reimth@...glemail.com> wrote:
> From: Thomas Reim <rdratlos@...oo.co.uk>
>
>    Some integrated ATI Radeon chipset implementations
>    with add-on HDMI card (e. g. Asus M2A-VM HDMI) indicate the availability
>    of a DDC even when the add-on card is not plugged in or HDMI is disabled
>    in BIOS setup. In this case, drm_get_edid() and drm_edid_block_valid()
>    periodically dump data and kernel errors into system log files and onto
>    terminals. For these chipsets DDC probing is extended by a check for a
>    correct EDID header. Only in case a valid EDID header is also found, the
>    (HDMI) connector will be used by the Radeon driver. This prevents the
>    kernel driver from useless flooding of logs and terminal sessions with
>    EDID dumps and error messages.
>    This patch adds a flag 'requires_extended_probe' to the radeon_connector
>    structure. In function radeon_connector_needs_extended_probe() this flag
>    can be set on a chipset family/vendor/connector type specific basis.
>    In addition, function drm_edid_header_is_valid() has been added for EDID
>    header check and function radeon_ddc_probe() has been adapted to perform
>    extended DDC probing if required by the connector's flag.
>
>    Tested for kernel 2.35, 2.38 and 3.0 on Asus M2A-VM HDMI board
>

Once it's ready, just add:
Cc: stable@...nel.org
to the commit message and it will go into the stable kernels as well.
Might want to mention the bug report in your commit message as well.
Just a couple comments below.  With those fixed:

Reviewed-by: Alex Deucher <alexdeucher@...il.com>

> Signed-off-by: Thomas Reim <rdratlos@...oo.co.uk>
> ---
>  drivers/gpu/drm/drm_edid.c                 |   24 +++++++++++----
>  drivers/gpu/drm/radeon/radeon_connectors.c |   45 ++++++++++++++++++++++++++--
>  drivers/gpu/drm/radeon/radeon_device.c     |    7 ++++-
>  drivers/gpu/drm/radeon/radeon_display.c    |    9 +++++
>  drivers/gpu/drm/radeon/radeon_i2c.c        |   32 +++++++++++++++-----
>  drivers/gpu/drm/radeon/radeon_mode.h       |    6 +++-
>  include/drm/drm_crtc.h                     |    1 +
>  7 files changed, 105 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 0929219..1bbb85b 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -127,6 +127,23 @@ static const u8 edid_header[] = {
>        0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00
>  };
>
> + /*
> + * Sanity check the header of the base EDID block.  Return 8 if the header
> + * is perfect, down to 0 if it's totally wrong.
> + */
> +int drm_edid_header_is_valid(const u8 *raw_edid)
> +{
> +       int i, score = 0;
> +
> +       for (i = 0; i < sizeof(edid_header); i++)
> +               if (raw_edid[i] == edid_header[i])
> +                       score++;
> +
> +       return score;
> +}
> +EXPORT_SYMBOL(drm_edid_header_is_valid);
> +
> +
>  /*
>  * Sanity check the EDID block (base or extension).  Return 0 if the block
>  * doesn't check out, or 1 if it's valid.
> @@ -139,12 +156,7 @@ drm_edid_block_valid(u8 *raw_edid)
>        struct edid *edid = (struct edid *)raw_edid;
>
>        if (raw_edid[0] == 0x00) {
> -               int score = 0;
> -
> -               for (i = 0; i < sizeof(edid_header); i++)
> -                       if (raw_edid[i] == edid_header[i])
> -                               score++;
> -
> +               int score = drm_edid_header_is_valid(raw_edid);
>                if (score == 8) ;
>                else if (score >= 6) {
>                        DRM_DEBUG("Fixing EDID header, your hardware may be failing\n");

Might want to break this hunk out as a separate patch.

> diff --git a/drivers/gpu/drm/radeon/radeon_connectors.c b/drivers/gpu/drm/radeon/radeon_connectors.c
> index cbfca3a..2e70be2 100644
> --- a/drivers/gpu/drm/radeon/radeon_connectors.c
> +++ b/drivers/gpu/drm/radeon/radeon_connectors.c
> @@ -424,6 +424,36 @@ int radeon_connector_set_property(struct drm_connector *connector, struct drm_pr
>        return 0;
>  }
>
> +/*
> + * Some integrated ATI Radeon chipset implementations (e. g.
> + * Asus M2A-VM HDMI) may indicate the availability of a DDC,
> + * even when there's no monitor connected. For these connectors
> + * following DDC probe extension will be applied: check also for the
> + * availability of EDID with at least a correct EDID header. Only then,
> + * DDC is assumed to be available. This prevents drm_get_edid() and
> + * drm_edid_block_valid() from periodically dumping data and kernel
> + * errors into the logs and onto the terminal.
> + */
> +static bool radeon_connector_needs_extended_probe(struct radeon_device *dev,
> +                                    uint32_t supported_device,
> +                                    int connector_type)
> +{
> +       /* Asus M2A-VM HDMI board sends data to i2c bus even,
> +        * if HDMI add-on card is not plugged in or HDMI is disabled in
> +        * BIOS. Valid DDC can only be assumed, if also a valid EDID header
> +        * can be retrieved via i2c bus during DDC probe */
> +       if ((dev->pdev->device == 0x791e) &&
> +           (dev->pdev->subsystem_vendor == 0x1043) &&
> +           (dev->pdev->subsystem_device == 0x826d)) {
> +               if ((connector_type == DRM_MODE_CONNECTOR_HDMIA) &&
> +                   (supported_device == ATOM_DEVICE_DFP2_SUPPORT))
> +                       return true;
> +       }
> +
> +       /* Default: no EDID header probe required for DDC probing */
> +       return false;
> +}
> +
>  static void radeon_fixup_lvds_native_mode(struct drm_encoder *encoder,
>                                          struct drm_connector *connector)
>  {
> @@ -655,7 +685,8 @@ radeon_vga_detect(struct drm_connector *connector, bool force)
>                ret = connector_status_disconnected;
>
>        if (radeon_connector->ddc_bus)
> -               dret = radeon_ddc_probe(radeon_connector);
> +               dret = radeon_ddc_probe(radeon_connector,
> +                                       radeon_connector->requires_extended_probe);
>        if (dret) {
>                if (radeon_connector->edid) {
>                        kfree(radeon_connector->edid);
> @@ -827,7 +858,8 @@ radeon_dvi_detect(struct drm_connector *connector, bool force)
>        bool dret = false;
>
>        if (radeon_connector->ddc_bus)
> -               dret = radeon_ddc_probe(radeon_connector);
> +               dret = radeon_ddc_probe(radeon_connector,
> +                                       radeon_connector->requires_extended_probe);
>        if (dret) {
>                if (radeon_connector->edid) {
>                        kfree(radeon_connector->edid);
> @@ -1245,7 +1277,8 @@ radeon_dp_detect(struct drm_connector *connector, bool force)
>                                if (radeon_dp_getdpcd(radeon_connector))
>                                        ret = connector_status_connected;
>                        } else {
> -                               if (radeon_ddc_probe(radeon_connector))
> +                               if (radeon_ddc_probe(radeon_connector,
> +                                                    radeon_connector->requires_extended_probe))
>                                        ret = connector_status_connected;
>                        }
>                }
> @@ -1400,6 +1433,9 @@ radeon_add_atom_connector(struct drm_device *dev,
>        radeon_connector->shared_ddc = shared_ddc;
>        radeon_connector->connector_object_id = connector_object_id;
>        radeon_connector->hpd = *hpd;
> +       radeon_connector->requires_extended_probe =
> +               radeon_connector_needs_extended_probe(rdev, supported_device,
> +                                                       connector_type);
>        radeon_connector->router = *router;
>        if (router->ddc_valid || router->cd_valid) {
>                radeon_connector->router_bus = radeon_i2c_lookup(rdev, &router->i2c_info);
> @@ -1746,6 +1782,9 @@ radeon_add_legacy_connector(struct drm_device *dev,
>        radeon_connector->devices = supported_device;
>        radeon_connector->connector_object_id = connector_object_id;
>        radeon_connector->hpd = *hpd;
> +       radeon_connector->requires_extended_probe =
> +               radeon_connector_needs_extended_probe(rdev, supported_device,
> +                                                       connector_type);
>        switch (connector_type) {
>        case DRM_MODE_CONNECTOR_VGA:
>                drm_connector_init(dev, &radeon_connector->base, &radeon_vga_connector_funcs, connector_type);
> diff --git a/drivers/gpu/drm/radeon/radeon_device.c b/drivers/gpu/drm/radeon/radeon_device.c
> index 7cfaa7e..cbdac3d 100644
> --- a/drivers/gpu/drm/radeon/radeon_device.c
> +++ b/drivers/gpu/drm/radeon/radeon_device.c
> @@ -704,8 +704,13 @@ int radeon_device_init(struct radeon_device *rdev,
>        rdev->gpu_lockup = false;
>        rdev->accel_working = false;
>
> -       DRM_INFO("initializing kernel modesetting (%s 0x%04X:0x%04X).\n",
> +       if (pdev->subsystem_vendor == 0)
> +               DRM_INFO("initializing kernel modesetting (%s 0x%04X:0x%04X).\n",
>                radeon_family_name[rdev->family], pdev->vendor, pdev->device);
> +       else
> +               DRM_INFO("initializing kernel modesetting (%s 0x%04X:0x%04X 0x%04X:0x%04X).\n",
> +               radeon_family_name[rdev->family], pdev->vendor, pdev->device,
> +               pdev->subsystem_vendor, pdev->subsystem_device);
>

No need for the if block.  Just always print both the pci and
subsystem ids.  Also, I'd suggest making that a separate patch as it's
not related to the actual fix.


>        /* mutex initialization are all done here so we
>         * can recall function without having locking issues */
> diff --git a/drivers/gpu/drm/radeon/radeon_display.c b/drivers/gpu/drm/radeon/radeon_display.c
> index 292f73f..ed085ce 100644
> --- a/drivers/gpu/drm/radeon/radeon_display.c
> +++ b/drivers/gpu/drm/radeon/radeon_display.c
> @@ -777,8 +777,17 @@ static int radeon_ddc_dump(struct drm_connector *connector)
>        if (!radeon_connector->ddc_bus)
>                return -1;
>        edid = drm_get_edid(connector, &radeon_connector->ddc_bus->adapter);
> +       /* Log EDID retrieval status here. In particular with regard to
> +        * connectors with requires_extended_probe flag set, that will prevent
> +        * function radeon_dvi_detect() to fetch EDID on this connector,
> +        * as long as there is no valid EDID header found */
>        if (edid) {
> +               DRM_INFO("Radeon display connector %s: Found valid EDID",
> +                               drm_get_connector_name(connector));
>                kfree(edid);
> +       } else {
> +               DRM_INFO("Radeon display connector %s: No monitor connected or invalid EDID",
> +                               drm_get_connector_name(connector));
>        }
>        return ret;
>  }
> diff --git a/drivers/gpu/drm/radeon/radeon_i2c.c b/drivers/gpu/drm/radeon/radeon_i2c.c
> index 781196d..6c111c1 100644
> --- a/drivers/gpu/drm/radeon/radeon_i2c.c
> +++ b/drivers/gpu/drm/radeon/radeon_i2c.c
> @@ -32,17 +32,17 @@
>  * radeon_ddc_probe
>  *
>  */
> -bool radeon_ddc_probe(struct radeon_connector *radeon_connector)
> +bool radeon_ddc_probe(struct radeon_connector *radeon_connector, bool requires_extended_probe)
>  {
> -       u8 out_buf[] = { 0x0, 0x0};
> -       u8 buf[2];
> +       u8 out = 0x0;
> +       u8 buf[8];
>        int ret;
>        struct i2c_msg msgs[] = {
>                {
>                        .addr = 0x50,
>                        .flags = 0,
>                        .len = 1,
> -                       .buf = out_buf,
> +                       .buf = &out,
>                },
>                {
>                        .addr = 0x50,
> @@ -52,15 +52,31 @@ bool radeon_ddc_probe(struct radeon_connector *radeon_connector)
>                }
>        };
>
> +       /* Read 8 bytes from i2c for extended probe of EDID header */
> +       if (requires_extended_probe)
> +               msgs[1].len = 8;
> +
>        /* on hw with routers, select right port */
>        if (radeon_connector->router.ddc_valid)
>                radeon_router_select_ddc_port(radeon_connector);
>
>        ret = i2c_transfer(&radeon_connector->ddc_bus->adapter, msgs, 2);
> -       if (ret == 2)
> -               return true;
> -
> -       return false;
> +       if (ret != 2)
> +               /* Couldn't find an accessible DDC on this connector */
> +               return false;
> +       if (requires_extended_probe) {
> +               /* Probe also for valid EDID header
> +                * EDID header starts with:
> +                * 0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x00.
> +                * Only the first 6 bytes must be valid as
> +                * drm_edid_block_valid() can fix the last 2 bytes */
> +               if (drm_edid_header_is_valid(buf) < 6) {
> +                       /* Couldn't find an accessible EDID on this
> +                        * connector */
> +                       return false;
> +               }
> +       }
> +       return true;
>  }
>
>  /* bit banging i2c */
> diff --git a/drivers/gpu/drm/radeon/radeon_mode.h b/drivers/gpu/drm/radeon/radeon_mode.h
> index 6df4e3c..d09031c 100644
> --- a/drivers/gpu/drm/radeon/radeon_mode.h
> +++ b/drivers/gpu/drm/radeon/radeon_mode.h
> @@ -438,6 +438,9 @@ struct radeon_connector {
>        struct radeon_i2c_chan *ddc_bus;
>        /* some systems have an hdmi and vga port with a shared ddc line */
>        bool shared_ddc;
> +       /* for some Radeon chip families we apply an additional EDID header
> +          check as part of the DDC probe */
> +       bool requires_extended_probe;
>        bool use_digital;
>        /* we need to mind the EDID between detect
>           and get modes due to analog/digital/tvencoder */
> @@ -514,7 +517,8 @@ extern void radeon_i2c_put_byte(struct radeon_i2c_chan *i2c,
>                                u8 val);
>  extern void radeon_router_select_ddc_port(struct radeon_connector *radeon_connector);
>  extern void radeon_router_select_cd_port(struct radeon_connector *radeon_connector);
> -extern bool radeon_ddc_probe(struct radeon_connector *radeon_connector);
> +extern bool radeon_ddc_probe(struct radeon_connector *radeon_connector,
> +                       bool requires_extended_probe);
>  extern int radeon_ddc_get_modes(struct radeon_connector *radeon_connector);
>
>  extern struct drm_encoder *radeon_best_encoder(struct drm_connector *connector);
> diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
> index 33d12f8..0ec3687 100644
> --- a/include/drm/drm_crtc.h
> +++ b/include/drm/drm_crtc.h
> @@ -802,6 +802,7 @@ extern struct drm_display_mode *drm_gtf_mode_complex(struct drm_device *dev,
>  extern int drm_add_modes_noedid(struct drm_connector *connector,
>                                int hdisplay, int vdisplay);
>
> +extern int drm_edid_header_is_valid(const u8 *raw_edid);
>  extern bool drm_edid_is_valid(struct edid *edid);
>  struct drm_display_mode *drm_mode_find_dmt(struct drm_device *dev,
>                                           int hsize, int vsize, int fresh);
> --
> 1.7.1
>
>
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