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drm/vc4: hdmi: Compute the CEC clock divider from the clock rate

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The CEC clock divider needs to output a frequency of 40kHz from the HSM
rate on the BCM2835. The driver used to have a fixed frequency for it,
but that changed for the BCM2711 and we now need to compute it
dynamically to maintain the proper rate.

Fixes: cd4cb49dc5bb ("drm/vc4: hdmi: Adjust HSM clock rate depending on pixel rate")
Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Acked-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Tested-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Link: https://patchwork.freedesktop.org/patch/msgid/20210111142309.193441-7-maxime@cerno.tech
(cherry picked from commit f1ceb9d10043683b89e5e5e5848fb4e855295762)
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
This commit is contained in:
Maxime Ripard 2021-01-11 15:23:00 +01:00 committed by Maarten Lankhorst
parent 4d8602b8ec
commit 163a3ef681
1 changed files with 3 additions and 1 deletions
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4
drivers/gpu/drm/vc4/vc4_hdmi.c
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@ -1599,6 +1599,7 @@ static int vc4_hdmi_cec_init(struct vc4_hdmi *vc4_hdmi)
{
struct cec_connector_info conn_info;
struct platform_device *pdev = vc4_hdmi->pdev;
u16 clk_cnt;
u32 value;
int ret;
@ -1624,8 +1625,9 @@ static int vc4_hdmi_cec_init(struct vc4_hdmi *vc4_hdmi)
* 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;
value |= VC4_HDMI_CEC_ADDR_MASK |
(4091 << VC4_HDMI_CEC_DIV_CLK_CNT_SHIFT);
(clk_cnt << VC4_HDMI_CEC_DIV_CLK_CNT_SHIFT);
HDMI_WRITE(HDMI_CEC_CNTRL_1, value);
ret = devm_request_threaded_irq(&pdev->dev, platform_get_irq(pdev, 0),
vc4_cec_irq_handler,