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clk: bcm: rpi: Turn firmware clock on/off when preparing/unpreparing

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Currently, when we prepare or unprepare RPi's clocks, we don't actually
enable/disable the firmware clock. This means that
`clk_disable_unprepare()` doesn't actually change the clock state at
all, nor does it lowers the clock rate.

From the Mailbox Property Interface documentation [1], we can see that
we should use `RPI_FIRMWARE_SET_CLOCK_STATE` to set the clock state
off/on. Therefore, use `RPI_FIRMWARE_SET_CLOCK_STATE` to create a
prepare and an unprepare hook for RPi's firmware clock.

As now the clocks are actually turned off, some of them are now marked
CLK_IS_CRITICAL, as those are required to be on during the whole system
operation.

Link: https://github.com/raspberrypi/firmware/wiki/Mailbox-property-interface [1]
Signed-off-by: Maíra Canal <mcanal@igalia.com>
Reviewed-by: Stefan Wahren <wahrenst@gmx.net>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
This commit is contained in:
Maíra Canal
2025-07-31 18:06:18 -03:00
committed by Stephen Boyd
parent 072ce917bf
commit 919d6924ae
1 changed files with 55 additions and 1 deletions
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56
drivers/clk/bcm/clk-raspberrypi.c
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@@ -68,6 +68,7 @@ struct raspberrypi_clk_variant {
char *clkdev;
unsigned long min_rate;
bool minimize;
u32 flags;
};
static struct raspberrypi_clk_variant
@@ -75,6 +76,7 @@ raspberrypi_clk_variants[RPI_FIRMWARE_NUM_CLK_ID] = {
[RPI_FIRMWARE_ARM_CLK_ID] = {
.export = true,
.clkdev = "cpu0",
.flags = CLK_IS_CRITICAL,
},
[RPI_FIRMWARE_CORE_CLK_ID] = {
.export = true,
@@ -90,6 +92,12 @@ raspberrypi_clk_variants[RPI_FIRMWARE_NUM_CLK_ID] = {
* always use the minimum the drivers will let us.
*/
.minimize = true,
/*
* It should never be disabled as it drives the bus for
* everything else.
*/
.flags = CLK_IS_CRITICAL,
},
[RPI_FIRMWARE_M2MC_CLK_ID] = {
.export = true,
@@ -115,6 +123,15 @@ raspberrypi_clk_variants[RPI_FIRMWARE_NUM_CLK_ID] = {
* drivers will let us.
*/
.minimize = true,
/*
* As mentioned above, this clock is disabled during boot,
* the firmware will skip the HSM initialization, resulting
* in a bus lockup. Therefore, make sure it's enabled
* during boot, but after it, it can be enabled/disabled
* by the driver.
*/
.flags = CLK_IGNORE_UNUSED,
},
[RPI_FIRMWARE_V3D_CLK_ID] = {
.export = true,
@@ -123,10 +140,12 @@ raspberrypi_clk_variants[RPI_FIRMWARE_NUM_CLK_ID] = {
[RPI_FIRMWARE_PIXEL_CLK_ID] = {
.export = true,
.minimize = true,
.flags = CLK_IS_CRITICAL,
},
[RPI_FIRMWARE_HEVC_CLK_ID] = {
.export = true,
.minimize = true,
.flags = CLK_IS_CRITICAL,
},
[RPI_FIRMWARE_ISP_CLK_ID] = {
.export = true,
@@ -135,6 +154,7 @@ raspberrypi_clk_variants[RPI_FIRMWARE_NUM_CLK_ID] = {
[RPI_FIRMWARE_PIXEL_BVB_CLK_ID] = {
.export = true,
.minimize = true,
.flags = CLK_IS_CRITICAL,
},
[RPI_FIRMWARE_VEC_CLK_ID] = {
.export = true,
@@ -265,7 +285,41 @@ static int raspberrypi_fw_dumb_determine_rate(struct clk_hw *hw,
return 0;
}
static int raspberrypi_fw_prepare(struct clk_hw *hw)
{
const struct raspberrypi_clk_data *data = clk_hw_to_data(hw);
struct raspberrypi_clk *rpi = data->rpi;
u32 state = RPI_FIRMWARE_STATE_ENABLE_BIT;
int ret;
ret = raspberrypi_clock_property(rpi->firmware, data,
RPI_FIRMWARE_SET_CLOCK_STATE, &state);
if (ret)
dev_err_ratelimited(rpi->dev,
"Failed to set clock %s state to on: %d\n",
clk_hw_get_name(hw), ret);
return ret;
}
static void raspberrypi_fw_unprepare(struct clk_hw *hw)
{
const struct raspberrypi_clk_data *data = clk_hw_to_data(hw);
struct raspberrypi_clk *rpi = data->rpi;
u32 state = 0;
int ret;
ret = raspberrypi_clock_property(rpi->firmware, data,
RPI_FIRMWARE_SET_CLOCK_STATE, &state);
if (ret)
dev_err_ratelimited(rpi->dev,
"Failed to set clock %s state to off: %d\n",
clk_hw_get_name(hw), ret);
}
static const struct clk_ops raspberrypi_firmware_clk_ops = {
.prepare = raspberrypi_fw_prepare,
.unprepare = raspberrypi_fw_unprepare,
.is_prepared = raspberrypi_fw_is_prepared,
.recalc_rate = raspberrypi_fw_get_rate,
.determine_rate = raspberrypi_fw_dumb_determine_rate,
@@ -295,7 +349,7 @@ static struct clk_hw *raspberrypi_clk_register(struct raspberrypi_clk *rpi,
if (!init.name)
return ERR_PTR(-ENOMEM);
init.ops = &raspberrypi_firmware_clk_ops;
init.flags = CLK_GET_RATE_NOCACHE;
init.flags = variant->flags | CLK_GET_RATE_NOCACHE;
data->hw.init = &init;