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Date: Wed, 15 Jan 2020 14:23:25 +0200 From: Stefan Mavrodiev <stefan@...mex.com> To: Maxime Ripard <mripard@...nel.org>, Stefan Mavrodiev <stefan@...mex.com> Cc: Dan Williams <dan.j.williams@...el.com>, Vinod Koul <vkoul@...nel.org>, Chen-Yu Tsai <wens@...e.org>, David Airlie <airlied@...ux.ie>, Daniel Vetter <daniel@...ll.ch>, open list <linux-kernel@...r.kernel.org>, "open list:DMA GENERIC OFFLOAD ENGINE SUBSYSTEM" <dmaengine@...r.kernel.org>, "moderated list:ARM/Allwinner sunXi SoC support" <linux-arm-kernel@...ts.infradead.org>, "open list:DRM DRIVERS FOR ALLWINNER A10" <dri-devel@...ts.freedesktop.org>, linux-sunxi@...glegroups.com Subject: Re: [PATCH 2/2] drm: sun4i: hdmi: Add support for sun4i HDMI encoder audio Hi, On 1/15/20 10:32 AM, Maxime Ripard wrote: > Hi Stefan, > > On Tue, Jan 14, 2020 at 11:04:55AM +0200, Stefan Mavrodiev wrote: >> On 1/10/20 6:26 PM, Maxime Ripard wrote: >>> Hi, >>> >>> On Fri, Jan 10, 2020 at 04:11:40PM +0200, Stefan Mavrodiev wrote: >>>> Add HDMI audio support for the sun4i-hdmi encoder, used on >>>> the older Allwinner chips - A10, A20, A31. >>>> >>>> Most of the code is based on the BSP implementation. In it >>>> dditional formats are supported (S20_3LE and S24_LE), however >>>> there where some problems with them and only S16_LE is left. >>>> >>>> Signed-off-by: Stefan Mavrodiev <stefan@...mex.com> >>>> --- >>>> drivers/gpu/drm/sun4i/Kconfig | 1 + >>>> drivers/gpu/drm/sun4i/Makefile | 1 + >>>> drivers/gpu/drm/sun4i/sun4i_hdmi.h | 30 ++ >>>> drivers/gpu/drm/sun4i/sun4i_hdmi_audio.c | 375 +++++++++++++++++++++++ >>>> drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c | 4 + >>>> 5 files changed, 411 insertions(+) >>>> create mode 100644 drivers/gpu/drm/sun4i/sun4i_hdmi_audio.c >>>> >>>> diff --git a/drivers/gpu/drm/sun4i/Kconfig b/drivers/gpu/drm/sun4i/Kconfig >>>> index 37e90e42943f..192b732b10cd 100644 >>>> --- a/drivers/gpu/drm/sun4i/Kconfig >>>> +++ b/drivers/gpu/drm/sun4i/Kconfig >>>> @@ -19,6 +19,7 @@ if DRM_SUN4I >>>> config DRM_SUN4I_HDMI >>>> tristate "Allwinner A10 HDMI Controller Support" >>>> default DRM_SUN4I >>>> + select SND_PCM_ELD >>>> help >>>> Choose this option if you have an Allwinner SoC with an HDMI >>>> controller. >>>> diff --git a/drivers/gpu/drm/sun4i/Makefile b/drivers/gpu/drm/sun4i/Makefile >>>> index 0d04f2447b01..e2d82b451c36 100644 >>>> --- a/drivers/gpu/drm/sun4i/Makefile >>>> +++ b/drivers/gpu/drm/sun4i/Makefile >>>> @@ -5,6 +5,7 @@ sun4i-frontend-y += sun4i_frontend.o >>>> sun4i-drm-y += sun4i_drv.o >>>> sun4i-drm-y += sun4i_framebuffer.o >>>> >>>> +sun4i-drm-hdmi-y += sun4i_hdmi_audio.o >>>> sun4i-drm-hdmi-y += sun4i_hdmi_ddc_clk.o >>>> sun4i-drm-hdmi-y += sun4i_hdmi_enc.o >>>> sun4i-drm-hdmi-y += sun4i_hdmi_i2c.o >>>> diff --git a/drivers/gpu/drm/sun4i/sun4i_hdmi.h b/drivers/gpu/drm/sun4i/sun4i_hdmi.h >>>> index 7ad3f06c127e..456964e681b0 100644 >>>> --- a/drivers/gpu/drm/sun4i/sun4i_hdmi.h >>>> +++ b/drivers/gpu/drm/sun4i/sun4i_hdmi.h >>>> @@ -42,7 +42,32 @@ >>>> #define SUN4I_HDMI_VID_TIMING_POL_VSYNC BIT(1) >>>> #define SUN4I_HDMI_VID_TIMING_POL_HSYNC BIT(0) >>>> >>>> +#define SUN4I_HDMI_AUDIO_CTRL_REG 0x040 >>>> +#define SUN4I_HDMI_AUDIO_CTRL_ENABLE BIT(31) >>>> +#define SUN4I_HDMI_AUDIO_CTRL_RESET BIT(30) >>>> + >>>> +#define SUN4I_HDMI_AUDIO_FMT_REG 0x048 >>>> +#define SUN4I_HDMI_AUDIO_FMT_SRC BIT(31) >>>> +#define SUN4I_HDMI_AUDIO_FMT_LAYOUT BIT(3) >>>> +#define SUN4I_HDMI_AUDIO_FMT_CH_CFG(n) (n - 1) >>> There's the issue multiple times in the headers, but you should wrap n >>> in parentheses to make sure we have no issue with precedence when >>> calling the macro. >>> >>>> +int sun4i_hdmi_audio_create(struct sun4i_hdmi *hdmi) >>>> +{ >>>> + struct snd_soc_card *card = &sun4i_hdmi_audio_card; >>>> + struct snd_soc_dai_link_component *comp; >>>> + struct snd_soc_dai_link *link; >>>> + int ret; >>>> + >>>> + ret = devm_snd_dmaengine_pcm_register(hdmi->dev, >>>> + &sun4i_hdmi_audio_pcm_config, 0); >>>> + if (ret) { >>>> + DRM_ERROR("Could not register PCM\n"); >>>> + return ret; >>>> + } >>>> + >>>> + ret = devm_snd_soc_register_component(hdmi->dev, >>>> + &sun4i_hdmi_audio_component, >>>> + &sun4i_hdmi_audio_dai, 1); >>>> + if (ret) { >>>> + DRM_ERROR("Could not register DAI\n"); >>>> + return ret; >>>> + } >>>> + >>>> + link = devm_kzalloc(hdmi->dev, sizeof(*link), GFP_KERNEL); >>>> + if (!link) >>>> + return -ENOMEM; >>>> + >>>> + comp = devm_kzalloc(hdmi->dev, sizeof(*comp) * 3, GFP_KERNEL); >>>> + if (!comp) >>>> + return -ENOMEM; >>>> + >>>> + link->cpus = &comp[0]; >>>> + link->codecs = &comp[1]; >>>> + link->platforms = &comp[2]; >>>> + >>>> + link->num_cpus = 1; >>>> + link->num_codecs = 1; >>>> + link->num_platforms = 1; >>>> + >>>> + link->playback_only = 1; >>>> + >>>> + link->name = "SUN4I-HDMI"; >>>> + link->stream_name = "SUN4I-HDMI PCM"; >>>> + >>>> + link->codecs->name = dev_name(hdmi->dev); >>>> + link->codecs->dai_name = sun4i_hdmi_audio_dai.name; >>>> + >>>> + link->cpus->dai_name = dev_name(hdmi->dev); >>>> + >>>> + link->platforms->name = dev_name(hdmi->dev); >>>> + >>>> + link->dai_fmt = SND_SOC_DAIFMT_I2S; >>>> + >>>> + card->dai_link = link; >>>> + card->num_links = 1; >>>> + card->dev = hdmi->dev; >>>> + >>>> + snd_soc_card_set_drvdata(card, hdmi); >>>> + return devm_snd_soc_register_card(hdmi->dev, card); >>> Out of curiosity, did you try to remove the module with that patch >>> applied? IIRC, these functions will overwrite the device drvdata, and >>> we will try to access them in unbind / remove. >> Actually I did not. Just tried that and you're right. The module >> crashes at the unbind call. I use sun4i_hdmi struct only for >> regmap. Maybe create separate private structure and copy only >> regmap? > I think the issue is that: > > - In bind, we first call dev_set_drvdata on the bound device, with a > pointer to struct sun4i_hdmi as the value. The driver_data field > in struct device is now a pointer to our instance of struct > sun4i_hdmi. > > - In audio create, you then call snd_soc_card_set_drvdata with a > pointer to struct sun4i_hdmi as the value. The drvdata field in > the struct snd_soc_card is now a pointer to our instance of struct > sun4i_hdmi (so far so good). > > - Then you call (devm_)snd_soc_register_card. One of the thing that > it will do is call drv_set_drvdata on the card->dev device, > setting it to our pointer to the struct snd_soc_card we provided. > However, since you set card->dev to the same device than the one > initially bound, this means that you just overwrote the struct > sun4i_hdmi pointer with a pointer to struct snd_soc_card. > > - The driver will operate properly, since we never really use the > driver_data field, in the HDMI driver, except when... > > - At unbind, you retrieve the driver_data field, expecting a struct > sun4i_hdmi pointer, except you have a pointer to struct > snd_soc_card, and everything explodes. > > I think the way to work around that would be to create a new > (platform_)device for the HDMI audio component, so that ASoC can work > on that device instead. > > This seems to be what dw-hdmi is doing here: > https://elixir.bootlin.com/linux/latest/source/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c#L2812 > > (Except that they are also using platform_data, since they have > multiple drivers, we wouldn't, so we can just lookup sun4i_hdmi using > the parent's device driver_data). > >>>> +} >>>> diff --git a/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c b/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c >>>> index a7c4654445c7..79ecd89fb705 100644 >>>> --- a/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c >>>> +++ b/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c >>>> @@ -114,6 +114,9 @@ static void sun4i_hdmi_enable(struct drm_encoder *encoder) >>>> val |= SUN4I_HDMI_VID_CTRL_HDMI_MODE; >>>> >>>> writel(val, hdmi->base + SUN4I_HDMI_VID_CTRL_REG); >>>> + >>>> + if (hdmi->hdmi_audio && sun4i_hdmi_audio_create(hdmi)) >>>> + DRM_ERROR("Couldn't create the HDMI audio adapter\n"); >>> So you create the audio card each time the display is enabled? I guess >>> this is to deal with the hotplug? >> Yes. See below. >> >>> I'm not sure this is the right thing to do. If I remember well, the >>> ELD are here precisely to let userspace know that the display is >>> plugged (and audio-capable) or not. >>> >>> Also, you don't remove that card in the disable, which mean that if >>> you end up in a situation where you would enable the display, disable >>> it and then enable it again, you have two audio cards now. >> There is issue with the hotplug. When inserting the cable, the event >> is detected and the hdmi encoder is enabled. Thus the card is >> created. However further removal and insertions are not >> detected. > I guess we would need to fix that then? > >> This is why I don't remove the card. >> >> Also I count on devm_snd_soc_register_card() to release the card. > I think you should really create the card all the time, and just > update the ELD to let the userspace know when something has been > created. > > And yeah, we should have a working hotplug, but that's a separate > story :) Thank you for the review. Soon I'll prepare v2. Also I'll check the hotplug issue. > > Maxime Best regards, Stefan
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