From d1c0b7de4dfa5505cf7a1d6220aa72aace4435d0 Mon Sep 17 00:00:00 2001 From: Maxime Ripard Date: Fri, 2 Sep 2022 16:41:11 +0200 Subject: drm/vc4: Add module dependency on hdmi-codec The VC4 HDMI controller driver relies on the HDMI codec ASoC driver. In order to set it up properly, in vc4_hdmi_audio_init(), our HDMI driver will register a device matching the HDMI codec driver, and then register an ASoC card using that codec. However, if vc4 is compiled as a module, chances are that the hdmi-codec driver will be too. In such a case, the module loader will have a very narrow window to load the module between the device registration and the card registration. If it fails to load the module in time, the card registration will fail with EPROBE_DEFER, and we'll abort the audio initialisation, unregistering the HDMI codec device in the process. The next time the bind callback will be run, it's likely that we end up missing that window again, effectively preventing vc4 to probe entirely. In order to prevent this, we can create a soft dependency of the vc4 driver on the HDMI codec one so that we're sure the HDMI codec will be loaded before the VC4 module is, and thus we'll never end up in the previous situation. Fixes: 91e99e113929 ("drm/vc4: hdmi: Register HDMI codec") Reviewed-by: Javier Martinez Canillas Signed-off-by: Maxime Ripard Link: https://patchwork.freedesktop.org/patch/msgid/20220902144111.3424560-1-maxime@cerno.tech --- drivers/gpu/drm/vc4/vc4_drv.c | 1 + 1 file changed, 1 insertion(+) (limited to 'drivers') diff --git a/drivers/gpu/drm/vc4/vc4_drv.c b/drivers/gpu/drm/vc4/vc4_drv.c index 292d1b6a01b6..3dc01af0f90f 100644 --- a/drivers/gpu/drm/vc4/vc4_drv.c +++ b/drivers/gpu/drm/vc4/vc4_drv.c @@ -480,6 +480,7 @@ module_init(vc4_drm_register); module_exit(vc4_drm_unregister); MODULE_ALIAS("platform:vc4-drm"); +MODULE_SOFTDEP("pre: snd-soc-hdmi-codec"); MODULE_DESCRIPTION("Broadcom VC4 DRM Driver"); MODULE_AUTHOR("Eric Anholt "); MODULE_LICENSE("GPL v2"); -- cgit v1.2.3-59-g8ed1b From ae71ab585c819f83aec84f91eb01157a90552ef2 Mon Sep 17 00:00:00 2001 From: Maxime Ripard Date: Thu, 29 Sep 2022 11:21:17 +0200 Subject: drm/vc4: hdmi: Enforce the minimum rate at runtime_resume This is a revert of commit fd5894fa2413 ("drm/vc4: hdmi: Remove clock rate initialization"), with the code slightly moved around. It turns out that we can't downright remove that code from the driver, since the Pi0-3 and Pi4 are in different cases, and it only works for the Pi4. Indeed, the commit mentioned above was relying on the RaspberryPi firmware clocks driver to initialize the rate if it wasn't done by the firmware. However, the Pi0-3 are using the clk-bcm2835 clock driver that wasn't doing this initialization. We therefore end up with the clock not being assigned a rate, and the CPU stalling when trying to access a register. We can't move that initialization in the clk-bcm2835 driver, since the HSM clock we depend on is actually part of the HDMI power domain, so any rate setup is only valid when the power domain is enabled. Thus, we reinstated the minimum rate setup at runtime_suspend, which should address both issues. Link: https://lore.kernel.org/dri-devel/20220922145448.w3xfywkn5ecak2et@pengutronix.de/ Fixes: fd5894fa2413 ("drm/vc4: hdmi: Remove clock rate initialization") Reported-by: Marc Kleine-Budde Reviewed-by: Javier Martinez Canillas Tested-by: Stefan Wahren Signed-off-by: Maxime Ripard Link: https://patchwork.freedesktop.org/patch/msgid/20220929-rpi-pi3-unplugged-fixes-v1-1-cd22e962296c@cerno.tech --- drivers/gpu/drm/vc4/vc4_hdmi.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'drivers') diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c index 1e5f68704d7d..780a19a75c3f 100644 --- a/drivers/gpu/drm/vc4/vc4_hdmi.c +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c @@ -2871,6 +2871,15 @@ static int vc4_hdmi_runtime_resume(struct device *dev) u32 __maybe_unused value; int ret; + /* + * The HSM clock is in the HDMI power domain, so we need to set + * its frequency while the power domain is active so that it + * keeps its rate. + */ + ret = clk_set_min_rate(vc4_hdmi->hsm_clock, HSM_MIN_CLOCK_FREQ); + if (ret) + return ret; + ret = clk_prepare_enable(vc4_hdmi->hsm_clock); if (ret) return ret; -- cgit v1.2.3-59-g8ed1b From 4190e8bbcbc77a9c36724681801cedc5229e7fc2 Mon Sep 17 00:00:00 2001 From: Maxime Ripard Date: Thu, 29 Sep 2022 11:21:18 +0200 Subject: drm/vc4: hdmi: Check the HSM rate at runtime_resume If our HSM clock has not been properly initialized, any register access will silently lock up the system. Let's check that this can't happen by adding a check for the rate before any register access, and error out otherwise. Link: https://lore.kernel.org/dri-devel/20220922145448.w3xfywkn5ecak2et@pengutronix.de/ Reviewed-by: Javier Martinez Canillas Tested-by: Stefan Wahren Signed-off-by: Maxime Ripard Link: https://patchwork.freedesktop.org/patch/msgid/20220929-rpi-pi3-unplugged-fixes-v1-2-cd22e962296c@cerno.tech --- drivers/gpu/drm/vc4/vc4_hdmi.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) (limited to 'drivers') diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c index 780a19a75c3f..874c6bd787c5 100644 --- a/drivers/gpu/drm/vc4/vc4_hdmi.c +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c @@ -2869,6 +2869,7 @@ static int vc4_hdmi_runtime_resume(struct device *dev) struct vc4_hdmi *vc4_hdmi = dev_get_drvdata(dev); unsigned long __maybe_unused flags; u32 __maybe_unused value; + unsigned long rate; int ret; /* @@ -2884,6 +2885,21 @@ static int vc4_hdmi_runtime_resume(struct device *dev) if (ret) return ret; + /* + * Whenever the RaspberryPi boots without an HDMI monitor + * plugged in, the firmware won't have initialized the HSM clock + * rate and it will be reported as 0. + * + * If we try to access a register of the controller in such a + * case, it will lead to a silent CPU stall. Let's make sure we + * prevent such a case. + */ + rate = clk_get_rate(vc4_hdmi->hsm_clock); + if (!rate) { + ret = -EINVAL; + goto err_disable_clk; + } + if (vc4_hdmi->variant->reset) vc4_hdmi->variant->reset(vc4_hdmi); @@ -2905,6 +2921,10 @@ static int vc4_hdmi_runtime_resume(struct device *dev) #endif return 0; + +err_disable_clk: + clk_disable_unprepare(vc4_hdmi->hsm_clock); + return ret; } static int vc4_hdmi_bind(struct device *dev, struct device *master, void *data) -- cgit v1.2.3-59-g8ed1b