On Mo, 2024-11-25 at 22:07 +0530, Parthiban Nallathambi wrote:
> On some platforms like Allwinner A133 with GE8300 includes
> reset control from reset control unit. Add reset control
> optionally from the devicetree.
>
> Signed-off-by: Parthiban Nallathambi <parthi...@linumiz.com>
> ---
> drivers/gpu/drm/imagination/pvr_device.h | 8 ++++++++
> drivers/gpu/drm/imagination/pvr_drv.c | 5 +++++
> drivers/gpu/drm/imagination/pvr_power.c | 16 +++++++++++++++-
> 3 files changed, 28 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/imagination/pvr_device.h
> b/drivers/gpu/drm/imagination/pvr_device.h
> index 6d0dfacb677b..21ec7dd64415 100644
> --- a/drivers/gpu/drm/imagination/pvr_device.h
> +++ b/drivers/gpu/drm/imagination/pvr_device.h
> @@ -23,6 +23,7 @@
> #include <linux/kernel.h>
> #include <linux/math.h>
> #include <linux/mutex.h>
> +#include <linux/reset.h>
> #include <linux/spinlock_types.h>
> #include <linux/timer.h>
> #include <linux/types.h>
> @@ -131,6 +132,13 @@ struct pvr_device {
> */
> struct clk *mem_clk;
>
> + /**
> + * @reset: Optional reset control
> + *
> + * This may be used on some platforms to reset the GPU module/IP.
> + */
> + struct reset_control *reset;
> +
> /** @irq: IRQ number. */
> int irq;
>
> diff --git a/drivers/gpu/drm/imagination/pvr_drv.c
> b/drivers/gpu/drm/imagination/pvr_drv.c
> index fb17196e05f4..d9b918410ea9 100644
> --- a/drivers/gpu/drm/imagination/pvr_drv.c
> +++ b/drivers/gpu/drm/imagination/pvr_drv.c
> @@ -36,6 +36,7 @@
> #include <linux/of_platform.h>
> #include <linux/platform_device.h>
> #include <linux/pm_runtime.h>
> +#include <linux/reset.h>
> #include <linux/xarray.h>
>
> /**
> @@ -1427,6 +1428,10 @@ pvr_probe(struct platform_device *plat_dev)
> pm_runtime_use_autosuspend(&plat_dev->dev);
> pvr_watchdog_init(pvr_dev);
>
> + pvr_dev->reset =
> devm_reset_control_get_optional_exclusive(&plat_dev->dev, "ahb");
> + if (PTR_ERR(pvr_dev->reset) == -EPROBE_DEFER)
> + return PTR_ERR(pvr_dev->reset);
pvr_dev->reset =
devm_reset_control_get_optional_exclusive(&plat_dev->dev, "ahb");
if (IS_ERR(pvr_dev->reset))
return PTR_ERR(pvr_dev->reset);
Please don't ignore errors. devm_reset_control_get_optional_exclusive()
returns NULL if the "ahb" reset control isn't specified in the device
tree, and the reset_control_assert/deassert() functions accept that as
a non-existing reset, see [1].
[1] https://docs.kernel.org/driver-api/reset.html#optional-resets
> +
> err = pvr_device_init(pvr_dev);
> if (err)
> goto err_watchdog_fini;
> diff --git a/drivers/gpu/drm/imagination/pvr_power.c
> b/drivers/gpu/drm/imagination/pvr_power.c
> index ba7816fd28ec..a24ed85f36c7 100644
> --- a/drivers/gpu/drm/imagination/pvr_power.c
> +++ b/drivers/gpu/drm/imagination/pvr_power.c
> @@ -15,6 +15,7 @@
> #include <linux/mutex.h>
> #include <linux/platform_device.h>
> #include <linux/pm_runtime.h>
> +#include <linux/reset.h>
> #include <linux/timer.h>
> #include <linux/types.h>
> #include <linux/workqueue.h>
> @@ -252,6 +253,9 @@ pvr_power_device_suspend(struct device *dev)
> clk_disable_unprepare(pvr_dev->sys_clk);
> clk_disable_unprepare(pvr_dev->core_clk);
>
> + if (!IS_ERR(pvr_dev->reset))
> + reset_control_assert(pvr_dev->reset);
reset_control_assert(pvr_dev->reset);
This just returns 0 if pvr_dev->reset == NULL.
> +
> err_drm_dev_exit:
> drm_dev_exit(idx);
>
> @@ -270,9 +274,15 @@ pvr_power_device_resume(struct device *dev)
> if (!drm_dev_enter(drm_dev, &idx))
> return -EIO;
>
> + if (!IS_ERR(pvr_dev->reset)) {
> + err = reset_control_reset(pvr_dev->reset);
> + if (err)
> + goto err_drm_dev_exit;
> + }
err = reset_control_reset(pvr_dev->reset);
if (err)
goto err_drm_dev_exit;
> +
> err = clk_prepare_enable(pvr_dev->core_clk);
> if (err)
> - goto err_drm_dev_exit;
> + goto err_reset_exit;
>
> err = clk_prepare_enable(pvr_dev->sys_clk);
> if (err)
> @@ -301,6 +311,10 @@ pvr_power_device_resume(struct device *dev)
> err_core_clk_disable:
> clk_disable_unprepare(pvr_dev->core_clk);
>
> +err_reset_exit:
> + if (!IS_ERR(pvr_dev->reset))
> + reset_control_assert(pvr_dev->reset);
err_reset_exit:
reset_control_assert(pvr_dev->reset);
> +
> err_drm_dev_exit:
> drm_dev_exit(idx);
>
>
regards
Philipp
