Hi Maxime
On Wed, 8 Jul 2020 at 18:43, Maxime Ripard <maxime@xxxxxxxxxx> wrote:
>
> The unbind function needs to retrieve a vc4_hdmi structure pointer through
> the struct device that we're given since we want to support multiple HDMI
> controllers.
>
> However, our optional ASoC support doesn't make that trivial since it will
> overwrite the device drvdata if we use it, but obviously won't if we don't
> use it.
>
> Let's make sure the fields are at the proper offset to be able to cast
> between the snd_soc_card structure and the vc4_hdmi structure
> transparently so we can support both cases.
>
> Signed-off-by: Maxime Ripard <maxime@xxxxxxxxxx>
Reviewed-by: Dave Stevenson <dave.stevenson@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/vc4/vc4_hdmi.c | 24 +++++++++++++++++++++++-
> drivers/gpu/drm/vc4/vc4_hdmi.h | 4 ++--
> 2 files changed, 25 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
> index 09b297a1b39d..7cd1394c10fa 100644
> --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
> +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
> @@ -1200,6 +1200,7 @@ static int vc4_hdmi_bind(struct device *dev, struct device *master, void *data)
> if (!vc4_hdmi)
> return -ENOMEM;
>
> + dev_set_drvdata(dev, vc4_hdmi);
> encoder = &vc4_hdmi->encoder.base.base;
> vc4_hdmi->encoder.base.type = VC4_ENCODER_TYPE_HDMI0;
> vc4_hdmi->pdev = pdev;
> @@ -1362,7 +1363,28 @@ static void vc4_hdmi_unbind(struct device *dev, struct device *master,
> {
> struct drm_device *drm = dev_get_drvdata(master);
> struct vc4_dev *vc4 = drm->dev_private;
> - struct vc4_hdmi *vc4_hdmi = vc4->hdmi;
> + struct vc4_hdmi *vc4_hdmi;
> +
> + /*
> + * ASoC makes it a bit hard to retrieve a pointer to the
> + * vc4_hdmi structure. Registering the card will overwrite our
> + * device drvdata with a pointer to the snd_soc_card structure,
> + * which can then be used to retrieve whatever drvdata we want
> + * to associate.
> + *
> + * However, that doesn't fly in the case where we wouldn't
> + * register an ASoC card (because of an old DT that is missing
> + * the dmas properties for example), then the card isn't
> + * registered and the device drvdata wouldn't be set.
> + *
> + * We can deal with both cases by making sure a snd_soc_card
> + * pointer and a vc4_hdmi structure are pointing to the same
> + * memory address, so we can treat them indistinctly without any
> + * issue.
> + */
> + BUILD_BUG_ON(offsetof(struct vc4_hdmi_audio, card) != 0);
> + BUILD_BUG_ON(offsetof(struct vc4_hdmi, audio) != 0);
> + vc4_hdmi = dev_get_drvdata(dev);
>
> cec_unregister_adapter(vc4_hdmi->cec_adap);
> vc4_hdmi_connector_destroy(&vc4_hdmi->connector.base);
> diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.h b/drivers/gpu/drm/vc4/vc4_hdmi.h
> index 749a807cd1f3..d43462789450 100644
> --- a/drivers/gpu/drm/vc4/vc4_hdmi.h
> +++ b/drivers/gpu/drm/vc4/vc4_hdmi.h
> @@ -53,13 +53,13 @@ struct vc4_hdmi_audio {
>
> /* General HDMI hardware state. */
> struct vc4_hdmi {
> + struct vc4_hdmi_audio audio;
> +
> struct platform_device *pdev;
>
> struct vc4_hdmi_encoder encoder;
> struct vc4_hdmi_connector connector;
>
> - struct vc4_hdmi_audio audio;
> -
> struct i2c_adapter *ddc;
> void __iomem *hdmicore_regs;
> void __iomem *hd_regs;
> --
> git-series 0.9.1
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