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From 3c33724058852d7c58d77d03e11ca545fb04256a Mon Sep 17 00:00:00 2001
From: Maxime Ripard <maxime@cerno.tech>
Date: Mon, 10 Feb 2020 15:23:06 +0100
Subject: [PATCH] drm/vc4: hdmi: Adjust HSM clock rate depending on
pixel rate
The HSM clock needs to be setup at around 110% of the pixel rate. This
was done previously by setting the clock rate to 148.5MHz * 108% at
probe time and only check in mode_valid whether the mode pixel clock was
under 148.5MHz or not.
However, with 4k we need to change that frequency to a higher frequency
than 148.5MHz.
Let's change that logic a bit by setting the clock rate of the HSM clock
to the pixel rate at encoder_enable time. This would work for the
BCM2711 that support 4k resolutions and has a clock that can provide it,
but we still have to take care of a 4k panel plugged on a BCM283x SoCs
that wouldn't be able to use those modes, so let's define the limit in
the variant.
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
---
drivers/gpu/drm/vc4/vc4_hdmi.c | 51 +++++++++++++++++-----------------
drivers/gpu/drm/vc4/vc4_hdmi.h | 3 ++
2 files changed, 29 insertions(+), 25 deletions(-)
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -52,7 +52,6 @@
#include "vc4_hdmi_regs.h"
#include "vc4_regs.h"
-#define HSM_CLOCK_FREQ 163682864
#define CEC_CLOCK_FREQ 40000
static int vc4_hdmi_debugfs_regs(struct seq_file *m, void *unused)
@@ -329,6 +328,7 @@ static void vc4_hdmi_encoder_disable(str
HDMI_WRITE(HDMI_VID_CTL,
HDMI_READ(HDMI_VID_CTL) & ~VC4_HD_VID_CTL_ENABLE);
+ clk_disable_unprepare(vc4_hdmi->hsm_clock);
clk_disable_unprepare(vc4_hdmi->pixel_clock);
ret = pm_runtime_put(&vc4_hdmi->pdev->dev);
@@ -426,6 +426,7 @@ static void vc4_hdmi_encoder_enable(stru
struct vc4_hdmi *vc4_hdmi = encoder_to_vc4_hdmi(encoder);
struct vc4_hdmi_encoder *vc4_encoder = to_vc4_hdmi_encoder(encoder);
bool debug_dump_regs = false;
+ unsigned long pixel_rate, hsm_rate;
int ret;
ret = pm_runtime_get_sync(&vc4_hdmi->pdev->dev);
@@ -434,9 +435,8 @@ static void vc4_hdmi_encoder_enable(stru
return;
}
- ret = clk_set_rate(vc4_hdmi->pixel_clock,
- mode->clock * 1000 *
- ((mode->flags & DRM_MODE_FLAG_DBLCLK) ? 2 : 1));
+ pixel_rate = mode->clock * 1000 * ((mode->flags & DRM_MODE_FLAG_DBLCLK) ? 2 : 1);
+ ret = clk_set_rate(vc4_hdmi->pixel_clock, pixel_rate);
if (ret) {
DRM_ERROR("Failed to set pixel clock rate: %d\n", ret);
return;
@@ -448,6 +448,24 @@ static void vc4_hdmi_encoder_enable(stru
return;
}
+ /*
+ * The HSM rate needs to be at 108% of the pixel clock, with a
+ * minimum of 108MHz.
+ */
+ hsm_rate = max_t(unsigned long, 108000000, (pixel_rate / 100) * 108);
+ ret = clk_set_rate(vc4_hdmi->hsm_clock, hsm_rate);
+ if (ret) {
+ DRM_ERROR("Failed to set HSM clock rate: %d\n", ret);
+ return;
+ }
+
+ ret = clk_prepare_enable(vc4_hdmi->hsm_clock);
+ if (ret) {
+ DRM_ERROR("Failed to turn on HSM clock: %d\n", ret);
+ clk_disable_unprepare(vc4_hdmi->pixel_clock);
+ return;
+ }
+
if (vc4_hdmi->variant->reset)
vc4_hdmi->variant->reset(vc4_hdmi);
@@ -578,7 +596,9 @@ vc4_hdmi_encoder_mode_valid(struct drm_e
* Additionally, the AXI clock needs to be at least 25% of
* pixel clock, but HSM ends up being the limiting factor.
*/
- if (mode->clock > HSM_CLOCK_FREQ / (1000 * 101 / 100))
+ struct vc4_hdmi *vc4_hdmi = encoder_to_vc4_hdmi(encoder);
+
+ if ((mode->clock * 1000) > vc4_hdmi->variant->max_pixel_clock)
return MODE_CLOCK_HIGH;
return MODE_OK;
@@ -1353,23 +1373,6 @@ static int vc4_hdmi_bind(struct device *
return -EPROBE_DEFER;
}
- /* This is the rate that is set by the firmware. The number
- * needs to be a bit higher than the pixel clock rate
- * (generally 148.5Mhz).
- */
- ret = clk_set_rate(vc4_hdmi->hsm_clock, HSM_CLOCK_FREQ);
- if (ret) {
- DRM_ERROR("Failed to set HSM clock rate: %d\n", ret);
- goto err_put_i2c;
- }
-
- ret = clk_prepare_enable(vc4_hdmi->hsm_clock);
- if (ret) {
- DRM_ERROR("Failed to turn on HDMI state machine clock: %d\n",
- ret);
- goto err_put_i2c;
- }
-
/* Only use the GPIO HPD pin if present in the DT, otherwise
* we'll use the HDMI core's register.
*/
@@ -1427,9 +1430,7 @@ err_destroy_conn:
err_destroy_encoder:
vc4_hdmi_encoder_destroy(encoder);
err_unprepare_hsm:
- clk_disable_unprepare(vc4_hdmi->hsm_clock);
pm_runtime_disable(dev);
-err_put_i2c:
put_device(&vc4_hdmi->ddc->dev);
return ret;
@@ -1452,7 +1453,6 @@ static void vc4_hdmi_unbind(struct devic
vc4_hdmi_connector_destroy(&vc4_hdmi->connector);
vc4_hdmi_encoder_destroy(&vc4_hdmi->encoder.base.base);
- clk_disable_unprepare(vc4_hdmi->hsm_clock);
pm_runtime_disable(dev);
put_device(&vc4_hdmi->ddc->dev);
@@ -1475,6 +1475,7 @@ static int vc4_hdmi_dev_remove(struct pl
}
static const struct vc4_hdmi_variant bcm2835_variant = {
+ .max_pixel_clock = 148500000,
.audio_available = true,
.cec_available = true,
.registers = vc4_hdmi_fields,
--- a/drivers/gpu/drm/vc4/vc4_hdmi.h
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.h
@@ -38,6 +38,9 @@ struct vc4_hdmi_variant {
/* Set to true when the CEC support is available */
bool cec_available;
+ /* Maximum pixel clock supported by the controller (in Hz) */
+ unsigned long long max_pixel_clock;
+
/* List of the registers available on that variant */
const struct vc4_hdmi_register *registers;
|
