* Re:[PATCH linux-next] drm/i915/display: Remove unused variable and its assignment.
@ 2021-10-19 2:24 ` luo.penghao
0 siblings, 0 replies; 4+ messages in thread
From: luo.penghao @ 2021-10-19 2:24 UTC (permalink / raw)
To: ville.syrjala
Cc: cgel.zte, jani.nikula, joonas.lahtinen, rodrigo.vivi, airlied,
daniel, sfr, intel-gfx, dri-devel
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> This one we could use. For some reason we hardcode it to
> 1 now, which is correct for our use cases but I don't really> see a reason to hardcode it here. We are supposed to calculate> it correctly after all, and chv_crtc_clock_get() also just blindly> reads it out.> > > bestm2_frac = crtc_state->dpll.m2 & 0x3fffff;> > - bestm1 = crtc_state->dpll.m1;> > This one is a bit trickier since I don't think the spec even> gives us other values. But we could assert that it's correct.> > Some something along these lines I think would be best:> + drm_WARN_ON(&dev_priv->drm, bestm1 != 2);> vlv_dpio_write(dev_priv, pipe, CHV_PLL_DW1(port),> DPIO_CHV_M1_DIV_BY_2 |> - 1 << DPIO_CHV_N_DIV_SHIFT);> + bestn << DPIO_CHV_N_DIV_SHIFT);
Thanks for your kind response ! Does that means the variable will be
used by the hardware?if so as far as I see it, I don't seem to see the
relevant interface.
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Intel-gfx] [PATCH linux-next] drm/i915/display: Remove unused variable and its assignment.
@ 2021-10-19 2:24 ` luo.penghao
0 siblings, 0 replies; 4+ messages in thread
From: luo.penghao @ 2021-10-19 2:24 UTC (permalink / raw)
To: ville.syrjala
Cc: cgel.zte, jani.nikula, joonas.lahtinen, rodrigo.vivi, airlied,
daniel, sfr, intel-gfx, dri-devel
[-- Attachment #1.1.1: Type: text/plain, Size: 963 bytes --]
> This one we could use. For some reason we hardcode it to
> 1 now, which is correct for our use cases but I don't really> see a reason to hardcode it here. We are supposed to calculate> it correctly after all, and chv_crtc_clock_get() also just blindly> reads it out.> > > bestm2_frac = crtc_state->dpll.m2 & 0x3fffff;> > - bestm1 = crtc_state->dpll.m1;> > This one is a bit trickier since I don't think the spec even> gives us other values. But we could assert that it's correct.> > Some something along these lines I think would be best:> + drm_WARN_ON(&dev_priv->drm, bestm1 != 2);> vlv_dpio_write(dev_priv, pipe, CHV_PLL_DW1(port),> DPIO_CHV_M1_DIV_BY_2 |> - 1 << DPIO_CHV_N_DIV_SHIFT);> + bestn << DPIO_CHV_N_DIV_SHIFT);
Thanks for your kind response ! Does that means the variable will be
used by the hardware?if so as far as I see it, I don't seem to see the
relevant interface.
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re:[PATCH linux-next] drm/i915/display: Remove unused variable and its assignment.
@ 2021-10-19 2:23 luo.penghao
0 siblings, 0 replies; 4+ messages in thread
From: luo.penghao @ 2021-10-19 2:23 UTC (permalink / raw)
To: ville.syrjala
Cc: cgel.zte, jani.nikula, joonas.lahtinen, rodrigo.vivi, airlied,
daniel, sfr, intel-gfx, dri-devel, zealci
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> This one we could use. For some reason we hardcode it to
> 1 now, which is correct for our use cases but I don't really> see a reason to hardcode it here. We are supposed to calculate> it correctly after all, and chv_crtc_clock_get() also just blindly> reads it out.> > > bestm2_frac = crtc_state->dpll.m2 & 0x3fffff;> > - bestm1 = crtc_state->dpll.m1;> > This one is a bit trickier since I don't think the spec even> gives us other values. But we could assert that it's correct.> > Some something along these lines I think would be best:> + drm_WARN_ON(&dev_priv->drm, bestm1 != 2);> vlv_dpio_write(dev_priv, pipe, CHV_PLL_DW1(port),> DPIO_CHV_M1_DIV_BY_2 |> - 1 << DPIO_CHV_N_DIV_SHIFT);> + bestn << DPIO_CHV_N_DIV_SHIFT);
Thanks for your kind response ! Does that means the variable will be
used by the hardware?if so as far as I see it, I don't seem to see the
relevant interface.
[-- Attachment #1.1.2: Type: text/html , Size: 2820 bytes --]
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH linux-next] drm/i915/display: Remove unused variable and its assignment.
@ 2021-10-18 8:57 Ville Syrjälä
2021-10-19 2:22 ` luo.penghao
0 siblings, 1 reply; 4+ messages in thread
From: Ville Syrjälä @ 2021-10-18 8:57 UTC (permalink / raw)
To: luo penghao
Cc: Jani Nikula, Joonas Lahtinen, Rodrigo Vivi, David Airlie,
Daniel Vetter, Stephen Rothwell, intel-gfx, dri-devel,
linux-kernel, luo penghao, Zeal Robot
On Mon, Oct 18, 2021 at 08:43:31AM +0000, luo penghao wrote:
> Variable is not used in functions, and its assignment is redundant too.
> So it should be deleted.
>
> The clang_analyzer complains as follows:
>
> drivers/gpu/drm/i915/display/intel_dpll.c:1653:2 warning:
> Value stored to 'bestm1' is never read.
>
> drivers/gpu/drm/i915/display/intel_dpll.c:1651:2 warning:
> Value stored to 'bestn' is never read.
>
> Reported-by: Zeal Robot <zealci@zte.com.cn>
> Signed-off-by: luo penghao <luo.penghao@zte.com.cn>
> ---
> drivers/gpu/drm/i915/display/intel_dpll.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dpll.c b/drivers/gpu/drm/i915/display/intel_dpll.c
> index b84ed4a..28b1616 100644
> --- a/drivers/gpu/drm/i915/display/intel_dpll.c
> +++ b/drivers/gpu/drm/i915/display/intel_dpll.c
> @@ -1644,13 +1644,11 @@ static void chv_prepare_pll(const struct intel_crtc_state *crtc_state)
> enum pipe pipe = crtc->pipe;
> enum dpio_channel port = vlv_pipe_to_channel(pipe);
> u32 loopfilter, tribuf_calcntr;
> - u32 bestn, bestm1, bestm2, bestp1, bestp2, bestm2_frac;
> + u32 bestm2, bestp1, bestp2, bestm2_frac;
> u32 dpio_val;
> int vco;
>
> - bestn = crtc_state->dpll.n;
This one we could use. For some reason we hardcode it to
1 now, which is correct for our use cases but I don't really
see a reason to hardcode it here. We are supposed to calculate
it correctly after all, and chv_crtc_clock_get() also just blindly
reads it out.
> bestm2_frac = crtc_state->dpll.m2 & 0x3fffff;
> - bestm1 = crtc_state->dpll.m1;
This one is a bit trickier since I don't think the spec even
gives us other values. But we could assert that it's correct.
Some something along these lines I think would be best:
+ drm_WARN_ON(&dev_priv->drm, bestm1 != 2);
vlv_dpio_write(dev_priv, pipe, CHV_PLL_DW1(port),
DPIO_CHV_M1_DIV_BY_2 |
- 1 << DPIO_CHV_N_DIV_SHIFT);
+ bestn << DPIO_CHV_N_DIV_SHIFT);
--
Ville Syrjälä
Intel
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re:[PATCH linux-next] drm/i915/display: Remove unused variable and its assignment.
2021-10-18 8:57 [PATCH " Ville Syrjälä
@ 2021-10-19 2:22 ` luo.penghao
0 siblings, 0 replies; 4+ messages in thread
From: luo.penghao @ 2021-10-19 2:22 UTC (permalink / raw)
To: ville.syrjala
Cc: cgel.zte, jani.nikula, joonas.lahtinen, rodrigo.vivi, airlied,
daniel, sfr, intel-gfx, dri-devel, linux-kernel, zealci
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> This one we could use. For some reason we hardcode it to
> 1 now, which is correct for our use cases but I don't really> see a reason to hardcode it here. We are supposed to calculate> it correctly after all, and chv_crtc_clock_get() also just blindly> reads it out.> > > bestm2_frac = crtc_state->dpll.m2 & 0x3fffff;> > - bestm1 = crtc_state->dpll.m1;> > This one is a bit trickier since I don't think the spec even> gives us other values. But we could assert that it's correct.> > Some something along these lines I think would be best:> + drm_WARN_ON(&dev_priv->drm, bestm1 != 2);> vlv_dpio_write(dev_priv, pipe, CHV_PLL_DW1(port),> DPIO_CHV_M1_DIV_BY_2 |> - 1 << DPIO_CHV_N_DIV_SHIFT);> + bestn << DPIO_CHV_N_DIV_SHIFT);
Thanks for your kind response ! Does that means the variable will be
used by the hardware?if so as far as I see it, I don't seem to see the
relevant interface.
[-- Attachment #1.1.2: Type: text/html , Size: 2778 bytes --]
^ permalink raw reply [flat|nested] 4+ messages in thread
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2021-10-19 2:24 Re:[PATCH linux-next] drm/i915/display: Remove unused variable and its assignment luo.penghao
2021-10-19 2:24 ` [Intel-gfx] [PATCH " luo.penghao
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2021-10-19 2:23 luo.penghao
2021-10-18 8:57 [PATCH " Ville Syrjälä
2021-10-19 2:22 ` luo.penghao
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