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Date: Fri, 18 Dec 2020 12:25:00 +0000 From: Dave Stevenson <dave.stevenson@...pberrypi.com> To: Maxime Ripard <maxime@...no.tech> Cc: Eric Anholt <eric@...olt.net>, Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Thomas Zimmermann <tzimmermann@...e.de>, Daniel Vetter <daniel.vetter@...el.com>, David Airlie <airlied@...ux.ie>, Jason Cooper <jason@...edaemon.net>, bcm-kernel-feedback-list@...adcom.com, linux-arm-kernel@...ts.infradead.org, Marc Zyngier <maz@...nel.org>, Linux Media Mailing List <linux-media@...r.kernel.org>, Hans Verkuil <hverkuil-cisco@...all.nl>, LKML <linux-kernel@...r.kernel.org>, Mauro Carvalho Chehab <mchehab@...nel.org>, Thomas Gleixner <tglx@...utronix.de>, linux-rpi-kernel@...ts.infradead.org, DRI Development <dri-devel@...ts.freedesktop.org> Subject: Re: [PATCH 08/15] drm/vc4: hdmi: Introduce a CEC clock On Fri, 18 Dec 2020 at 12:23, Maxime Ripard <maxime@...no.tech> wrote: > > Hi Dave, > > On Fri, Dec 18, 2020 at 11:37:50AM +0000, Dave Stevenson wrote: > > Hi Maxime > > > > On Thu, 10 Dec 2020 at 13:47, Maxime Ripard <maxime@...no.tech> wrote: > > > > > > While the BCM2835 had the CEC clock derived from the HSM clock, the > > > BCM2711 has a dedicated parent clock for it. > > > > > > Let's introduce a separate clock for it so that we can handle both > > > cases. > > > > > > Signed-off-by: Maxime Ripard <maxime@...no.tech> > > > --- > > > drivers/gpu/drm/vc4/vc4_hdmi.c | 9 ++++++++- > > > drivers/gpu/drm/vc4/vc4_hdmi.h | 1 + > > > 2 files changed, 9 insertions(+), 1 deletion(-) > > > > > > diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c > > > index b93ee3e26e2b..0debd22bc992 100644 > > > --- a/drivers/gpu/drm/vc4/vc4_hdmi.c > > > +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c > > > @@ -145,7 +145,7 @@ static void vc4_hdmi_cec_update_clk_div(struct vc4_hdmi *vc4_hdmi) > > > * Set the clock divider: the hsm_clock rate and this divider > > > * setting will give a 40 kHz CEC clock. > > > */ > > > - clk_cnt = clk_get_rate(vc4_hdmi->hsm_clock) / CEC_CLOCK_FREQ; > > > + clk_cnt = clk_get_rate(vc4_hdmi->cec_clock) / CEC_CLOCK_FREQ; > > > value |= clk_cnt << VC4_HDMI_CEC_DIV_CLK_CNT_SHIFT; > > > HDMI_WRITE(HDMI_CEC_CNTRL_1, value); > > > } > > > @@ -1740,6 +1740,7 @@ static int vc4_hdmi_init_resources(struct vc4_hdmi *vc4_hdmi) > > > return PTR_ERR(vc4_hdmi->hsm_clock); > > > } > > > vc4_hdmi->audio_clock = vc4_hdmi->hsm_clock; > > > + vc4_hdmi->cec_clock = vc4_hdmi->hsm_clock; > > > > > > return 0; > > > } > > > @@ -1833,6 +1834,12 @@ static int vc5_hdmi_init_resources(struct vc4_hdmi *vc4_hdmi) > > > return PTR_ERR(vc4_hdmi->audio_clock); > > > } > > > > > > + vc4_hdmi->cec_clock = devm_clk_get(dev, "cec"); > > > + if (IS_ERR(vc4_hdmi->cec_clock)) { > > > + DRM_ERROR("Failed to get CEC clock\n"); > > > + return PTR_ERR(vc4_hdmi->cec_clock); > > > + } > > > > Aren't we adding to the DT binding here and breaking backwards compatibility? > > Admittedly CEC didn't work before (and was masked out) for vc5, but do > > we need to worry about those with existing DT files that currently > > work happily? > > The DT compatibility is not a worry here: I made sure the CEC clock and > range were part of the binding since it's been introduced: > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=2e3725b05b785e73482a194b99bff3d5a1c85140 > > So we were not using it so far, but it was in the DT all along I guess I should have read it then :-) In which case Reviewed-by: Dave Stevenson <dave.stevenson@...pberrypi.com>
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