Re: [Intel-gfx] [PATCH 04/13] drm/i915: Don't warn about zero N/P in *_calc_dpll_params()

2023-07-06 Thread Jani Nikula 
On Wed, 05 Jul 2023, Ville Syrjala  wrote:
> From: Ville Syrjälä 
>
> Allow *_calc_dpll_params() to be called even if the N/P dividers
> are zero without warning. We'll want to call these to make sure the
> derived values are fully computed, but not all users (VLV DSI in
> particular) don't even enable the DPLL and thus the dividers will
> be left at zero.
>
> It could also be possible that the BIOS has misprogrammed the DPLL
> (IIRC happened with some SNB machines with 4k+ displays) and thus
> we'll currently generate a lot of dmesg spew. Better be silent and
> just let the normal state checker/etc. deal with any driver bugs.
>
> Signed-off-by: Ville Syrjälä 

Reviewed-by: Jani Nikula 

> ---
>  drivers/gpu/drm/i915/display/intel_dpll.c | 37 ---
>  1 file changed, 20 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dpll.c 
> b/drivers/gpu/drm/i915/display/intel_dpll.c
> index 999badfe2906..71bfeea4cef2 100644
> --- a/drivers/gpu/drm/i915/display/intel_dpll.c
> +++ b/drivers/gpu/drm/i915/display/intel_dpll.c
> @@ -314,10 +314,11 @@ int pnv_calc_dpll_params(int refclk, struct dpll *clock)
>  {
>   clock->m = clock->m2 + 2;
>   clock->p = clock->p1 * clock->p2;
> - if (WARN_ON(clock->n == 0 || clock->p == 0))
> - return 0;
> - clock->vco = DIV_ROUND_CLOSEST(refclk * clock->m, clock->n);
> - clock->dot = DIV_ROUND_CLOSEST(clock->vco, clock->p);
> +
> + clock->vco = clock->n == 0 ? 0 :
> + DIV_ROUND_CLOSEST(refclk * clock->m, clock->n);
> + clock->dot = clock->p == 0 ? 0 :
> + DIV_ROUND_CLOSEST(clock->vco, clock->p);
>  
>   return clock->dot;
>  }
> @@ -331,10 +332,11 @@ int i9xx_calc_dpll_params(int refclk, struct dpll 
> *clock)
>  {
>   clock->m = i9xx_dpll_compute_m(clock);
>   clock->p = clock->p1 * clock->p2;
> - if (WARN_ON(clock->n + 2 == 0 || clock->p == 0))
> - return 0;
> - clock->vco = DIV_ROUND_CLOSEST(refclk * clock->m, clock->n + 2);
> - clock->dot = DIV_ROUND_CLOSEST(clock->vco, clock->p);
> +
> + clock->vco = clock->n + 2 == 0 ? 0 :
> + DIV_ROUND_CLOSEST(refclk * clock->m, clock->n + 2);
> + clock->dot = clock->p == 0 ? 0 :
> + DIV_ROUND_CLOSEST(clock->vco, clock->p);
>  
>   return clock->dot;
>  }
> @@ -343,10 +345,11 @@ int vlv_calc_dpll_params(int refclk, struct dpll *clock)
>  {
>   clock->m = clock->m1 * clock->m2;
>   clock->p = clock->p1 * clock->p2 * 5;
> - if (WARN_ON(clock->n == 0 || clock->p == 0))
> - return 0;
> - clock->vco = DIV_ROUND_CLOSEST(refclk * clock->m, clock->n);
> - clock->dot = DIV_ROUND_CLOSEST(clock->vco, clock->p);
> +
> + clock->vco = clock->n == 0 ? 0 :
> + DIV_ROUND_CLOSEST(refclk * clock->m, clock->n);
> + clock->dot = clock->p == 0 ? 0 :
> + DIV_ROUND_CLOSEST(clock->vco, clock->p);
>  
>   return clock->dot;
>  }
> @@ -355,11 +358,11 @@ int chv_calc_dpll_params(int refclk, struct dpll *clock)
>  {
>   clock->m = clock->m1 * clock->m2;
>   clock->p = clock->p1 * clock->p2 * 5;
> - if (WARN_ON(clock->n == 0 || clock->p == 0))
> - return 0;
> - clock->vco = DIV_ROUND_CLOSEST_ULL(mul_u32_u32(refclk, clock->m),
> -clock->n << 22);
> - clock->dot = DIV_ROUND_CLOSEST(clock->vco, clock->p);
> +
> + clock->vco = clock->n == 0 ? 0 :
> + DIV_ROUND_CLOSEST_ULL(mul_u32_u32(refclk, clock->m), clock->n 
> << 22);
> + clock->dot = clock->p == 0 ? 0 :
> + DIV_ROUND_CLOSEST(clock->vco, clock->p);
>  
>   return clock->dot;
>  }

-- 
Jani Nikula, Intel Open Source Graphics Center

[Intel-gfx] [PATCH 04/13] drm/i915: Don't warn about zero N/P in *_calc_dpll_params()

2023-07-05 Thread Ville Syrjala 
From: Ville Syrjälä 

Allow *_calc_dpll_params() to be called even if the N/P dividers
are zero without warning. We'll want to call these to make sure the
derived values are fully computed, but not all users (VLV DSI in
particular) don't even enable the DPLL and thus the dividers will
be left at zero.

It could also be possible that the BIOS has misprogrammed the DPLL
(IIRC happened with some SNB machines with 4k+ displays) and thus
we'll currently generate a lot of dmesg spew. Better be silent and
just let the normal state checker/etc. deal with any driver bugs.

Signed-off-by: Ville Syrjälä 
---
 drivers/gpu/drm/i915/display/intel_dpll.c | 37 ---
 1 file changed, 20 insertions(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dpll.c 
b/drivers/gpu/drm/i915/display/intel_dpll.c
index 999badfe2906..71bfeea4cef2 100644
--- a/drivers/gpu/drm/i915/display/intel_dpll.c
+++ b/drivers/gpu/drm/i915/display/intel_dpll.c
@@ -314,10 +314,11 @@ int pnv_calc_dpll_params(int refclk, struct dpll *clock)
 {
clock->m = clock->m2 + 2;
clock->p = clock->p1 * clock->p2;
-   if (WARN_ON(clock->n == 0 || clock->p == 0))
-   return 0;
-   clock->vco = DIV_ROUND_CLOSEST(refclk * clock->m, clock->n);
-   clock->dot = DIV_ROUND_CLOSEST(clock->vco, clock->p);
+
+   clock->vco = clock->n == 0 ? 0 :
+   DIV_ROUND_CLOSEST(refclk * clock->m, clock->n);
+   clock->dot = clock->p == 0 ? 0 :
+   DIV_ROUND_CLOSEST(clock->vco, clock->p);
 
return clock->dot;
 }
@@ -331,10 +332,11 @@ int i9xx_calc_dpll_params(int refclk, struct dpll *clock)
 {
clock->m = i9xx_dpll_compute_m(clock);
clock->p = clock->p1 * clock->p2;
-   if (WARN_ON(clock->n + 2 == 0 || clock->p == 0))
-   return 0;
-   clock->vco = DIV_ROUND_CLOSEST(refclk * clock->m, clock->n + 2);
-   clock->dot = DIV_ROUND_CLOSEST(clock->vco, clock->p);
+
+   clock->vco = clock->n + 2 == 0 ? 0 :
+   DIV_ROUND_CLOSEST(refclk * clock->m, clock->n + 2);
+   clock->dot = clock->p == 0 ? 0 :
+   DIV_ROUND_CLOSEST(clock->vco, clock->p);
 
return clock->dot;
 }
@@ -343,10 +345,11 @@ int vlv_calc_dpll_params(int refclk, struct dpll *clock)
 {
clock->m = clock->m1 * clock->m2;
clock->p = clock->p1 * clock->p2 * 5;
-   if (WARN_ON(clock->n == 0 || clock->p == 0))
-   return 0;
-   clock->vco = DIV_ROUND_CLOSEST(refclk * clock->m, clock->n);
-   clock->dot = DIV_ROUND_CLOSEST(clock->vco, clock->p);
+
+   clock->vco = clock->n == 0 ? 0 :
+   DIV_ROUND_CLOSEST(refclk * clock->m, clock->n);
+   clock->dot = clock->p == 0 ? 0 :
+   DIV_ROUND_CLOSEST(clock->vco, clock->p);
 
return clock->dot;
 }
@@ -355,11 +358,11 @@ int chv_calc_dpll_params(int refclk, struct dpll *clock)
 {
clock->m = clock->m1 * clock->m2;
clock->p = clock->p1 * clock->p2 * 5;
-   if (WARN_ON(clock->n == 0 || clock->p == 0))
-   return 0;
-   clock->vco = DIV_ROUND_CLOSEST_ULL(mul_u32_u32(refclk, clock->m),
-  clock->n << 22);
-   clock->dot = DIV_ROUND_CLOSEST(clock->vco, clock->p);
+
+   clock->vco = clock->n == 0 ? 0 :
+   DIV_ROUND_CLOSEST_ULL(mul_u32_u32(refclk, clock->m), clock->n 
<< 22);
+   clock->dot = clock->p == 0 ? 0 :
+   DIV_ROUND_CLOSEST(clock->vco, clock->p);
 
return clock->dot;
 }
-- 
2.39.3