Re: [PATCH 08/11] dmaengine: ste_dma40: Use power domain for LCLA SRAM

[Frank Li <Frank.li@oss.nxp.com>]

On Thu, Jun 18, 2026 at 07:00:54AM +0200, Linus Walleij wrote:
> Replace the LCLA ESRAM regulator with runtime PM.
>
> Use the SRAM device that owns the ESRAM34 power domain.
>
> Hold that domain while DMA transfers are active.
>
> Assisted-by: Codex:gpt-5-5
> Signed-off-by: Linus Walleij <linusw@kernel.org>
> ---
>  drivers/dma/ste_dma40.c | 97 ++++++++++++++++++++++++++++---------------------
>  1 file changed, 55 insertions(+), 42 deletions(-)
>
> diff --git a/drivers/dma/ste_dma40.c b/drivers/dma/ste_dma40.c
> index 9b803c0aec25..6ca67ec446dc 100644
> --- a/drivers/dma/ste_dma40.c
> +++ b/drivers/dma/ste_dma40.c
> @@ -21,8 +21,8 @@
>  #include <linux/of.h>
>  #include <linux/of_address.h>
>  #include <linux/of_dma.h>
> +#include <linux/of_platform.h>
>  #include <linux/amba/bus.h>
> -#include <linux/regulator/consumer.h>
>
>  #include "dmaengine.h"
>  #include "ste_dma40.h"
> @@ -571,7 +571,8 @@ struct d40_gen_dmac {
>   * to phy_chans entries.
>   * @plat_data: Pointer to provided platform_data which is the driver
>   * configuration.
> - * @lcpa_regulator: Pointer to hold the regulator for the esram bank for lcla.
> + * @lcla_dev: SRAM device for the ESRAM bank used by LCLA.
> + * @lcla_pm_enabled: Whether runtime PM was enabled for LCLA by this driver.
>   * @phy_res: Vector containing all physical channels.
>   * @lcla_pool: lcla pool settings and data.
>   * @lcpa_base: The virtual mapped address of LCPA.
> @@ -607,7 +608,8 @@ struct d40_base {
>  	struct d40_chan			**lookup_log_chans;
>  	struct d40_chan			**lookup_phy_chans;
>  	struct stedma40_platform_data	 *plat_data;
> -	struct regulator		 *lcpa_regulator;
> +	struct device			 *lcla_dev;
> +	bool				  lcla_pm_enabled;
>  	/* Physical half channels */
>  	struct d40_phy_res		 *phy_res;
>  	struct d40_lcla_pool		  lcla_pool;
> @@ -628,6 +630,22 @@ static struct device *chan2dev(struct d40_chan *d40c)
>  	return &d40c->chan.dev->device;
>  }
>
> +static void d40_transfer_runtime_get(struct d40_base *base)
> +{
> +	if (base->lcla_dev)
> +		pm_runtime_get_sync(base->lcla_dev);
> +
> +	pm_runtime_get_sync(base->dev);

Suggest create device link between base->dev and base->lcla_dev, so run
time pm framework will auto do it for you

Ref: https://lore.kernel.org/imx/20260513-b4-b4-edma-runtime-opt-v5-4-1e595bfb8423@nxp.com/

Frank