Re: [PATCH 05/20] drm/i915/dsi-pll: use generic poll_timeout_us() instead of wait_for()

["Hogander, Jouni" <jouni.hogander@intel.com>]

On Thu, 2025-08-28 at 15:20 +0300, Jani Nikula wrote:
> Prefer generic poll helpers over i915 custom helpers.
> 
> The functional change is losing the exponentially growing sleep of
> wait_for(), which used to be 10, 20, 40, ..., 640, and 1280 us.
> 
> Use an arbitrary constant 500 us sleep instead. The timeout remains
> at
> 20 ms.
> 
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>

Reviewed-by: Jouni Högander <jouni.hogander@intel.com>

> ---
>  drivers/gpu/drm/i915/display/vlv_dsi_pll.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/vlv_dsi_pll.c
> b/drivers/gpu/drm/i915/display/vlv_dsi_pll.c
> index 83afe1315e96..f078b9cda96c 100644
> --- a/drivers/gpu/drm/i915/display/vlv_dsi_pll.c
> +++ b/drivers/gpu/drm/i915/display/vlv_dsi_pll.c
> @@ -25,12 +25,12 @@
>   *	Yogesh Mohan Marimuthu <yogesh.mohan.marimuthu@intel.com>
>   */
>  
> +#include <linux/iopoll.h>
>  #include <linux/kernel.h>
>  #include <linux/string_helpers.h>
>  
>  #include <drm/drm_print.h>
>  
> -#include "i915_utils.h"
>  #include "intel_de.h"
>  #include "intel_display_types.h"
>  #include "intel_dsi.h"
> @@ -214,6 +214,8 @@ void vlv_dsi_pll_enable(struct intel_encoder
> *encoder,
>  			const struct intel_crtc_state *config)
>  {
>  	struct intel_display *display = to_intel_display(encoder);
> +	u32 val;
> +	int ret;
>  
>  	drm_dbg_kms(display->drm, "\n");
>  
> @@ -231,9 +233,10 @@ void vlv_dsi_pll_enable(struct intel_encoder
> *encoder,
>  
>  	vlv_cck_write(display->drm, CCK_REG_DSI_PLL_CONTROL, config-
> >dsi_pll.ctrl);
>  
> -	if (wait_for(vlv_cck_read(display->drm,
> CCK_REG_DSI_PLL_CONTROL) &
> -						DSI_PLL_LOCK, 20)) {
> -
> +	ret = poll_timeout_us(val = vlv_cck_read(display->drm,
> CCK_REG_DSI_PLL_CONTROL),
> +			      val & DSI_PLL_LOCK,
> +			      500, 20 * 1000, false);
> +	if (ret) {
>  		vlv_cck_put(display->drm);
>  		drm_err(display->drm, "DSI PLL lock failed\n");
>  		return;