On 7/17/21 4:21 PM, Qiang Yu wrote:
On Sat, Jul 17, 2021 at 9:08 PM Marek Vasut <marex@xxxxxxx> wrote:
On 7/17/21 2:34 PM, Qiang Yu wrote:
On Sat, Jul 17, 2021 at 2:20 AM Marek Vasut <marex@xxxxxxx> wrote:
Instead of requesting two separate clock and then handling them
separately in various places of the driver, use clk_bulk_*() API.
This permits handling devices with more than "bus"/"core" clock,
like ZynqMP, which has "gpu"/"gpu_pp0"/"gpu_pp1" all as separate
clock.
I can't find the ZynqMP DTS file under arch/arm64/boot/dts/xilinx
which has mali GPU node with an upstream kernel, where is it?
Posted here:
https://patchwork.kernel.org/project/linux-arm-kernel/patch/20210716182544.219490-1-marex@xxxxxxx/
So what's the relationship between "gpu" clk and "gpu_pp0"/"gpu_pp1"
clk? Do they need to be controlled separately or we can just control the
"gpu" clk? Because the devfreq code just controls a single module clk.
Per the docs, they are separate enable bits and the zynqmp clock
controller exports them as separate clock, see bits 24..26 here:
https://www.xilinx.com/html_docs/registers/ug1087/crf_apb___gpu_ref_ctrl.html
Signed-off-by: Marek Vasut <marex@xxxxxxx>
Cc: Qiang Yu <yuq825@xxxxxxxxx>
Cc: lima@xxxxxxxxxxxxxxxxxxxxx
---
drivers/gpu/drm/lima/lima_devfreq.c | 17 +++++++++---
drivers/gpu/drm/lima/lima_devfreq.h | 1 +
drivers/gpu/drm/lima/lima_device.c | 42 +++++++++++------------------
drivers/gpu/drm/lima/lima_device.h | 4 +--
4 files changed, 32 insertions(+), 32 deletions(-)
diff --git a/drivers/gpu/drm/lima/lima_devfreq.c b/drivers/gpu/drm/lima/lima_devfreq.c
index 8989e215dfc9..533b36932f79 100644
--- a/drivers/gpu/drm/lima/lima_devfreq.c
+++ b/drivers/gpu/drm/lima/lima_devfreq.c
@@ -58,7 +58,7 @@ static int lima_devfreq_get_dev_status(struct device *dev,
struct lima_devfreq *devfreq = &ldev->devfreq;
unsigned long irqflags;
- status->current_frequency = clk_get_rate(ldev->clk_gpu);
+ status->current_frequency = clk_get_rate(devfreq->clk_gpu);
spin_lock_irqsave(&devfreq->lock, irqflags);
@@ -110,12 +110,23 @@ int lima_devfreq_init(struct lima_device *ldev)
struct lima_devfreq *ldevfreq = &ldev->devfreq;
struct dev_pm_opp *opp;
unsigned long cur_freq;
- int ret;
+ int i, ret;
if (!device_property_present(dev, "operating-points-v2"))
/* Optional, continue without devfreq */
return 0;
+ /* Find first clock which are not "bus" clock */
+ for (i = 0; i < ldev->nr_clks; i++) {
+ if (!strcmp(ldev->clks[i].id, "bus"))
+ continue;
+ ldevfreq->clk_gpu = ldev->clks[i].clk;
+ break;
+ }
I'd prefer an explicit name for the required clk name. If some DTS has different
name other than "core" for the module clk (ie. "gpu"), it should be changed to
"core".
The problem here is, the zynqmp has no core clock, it has "gpu and both
pixel pipes" super-clock-gate which controls everything, and then
per-pixel-pipe sub-clock-gates.
So the "gpu" clk can gate both "gpu_pp0" and "gpu_pp1" clk, how about frequency?
I don't think it is a good idea to just gate off the root clock while
the sub-clock are still enabled. That might lead to latch ups (+CC
Michal, he might know more).
And who would enable the sub-clock anyway, it should be the GPU driver, no?
Can we set clock rate for "gpu" then "gpu_pp0" and "gpu_pp1" pass
through the same
rate? If so, "gpu" works just like "core".
I don't think the zynqmp is capable of any DVFS on the GPU at all, it
just runs at fixed frequency.
