linux-kernel - Re: [PATCH v5 04/12] drm: renesas: rz-du: mipi

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Message-ID: <CA+V-a8vn46BLWyn0DCp-6h3eZD8ef+r7vLCy6vkfkyehdM8d7g@mail.gmail.com>
Date: Wed, 21 May 2025 14:03:05 +0100
From: "Lad, Prabhakar" <prabhakar.csengg@...il.com>
To: Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc: Biju Das <biju.das.jz@...renesas.com>, David Airlie <airlied@...il.com>, 
	Simona Vetter <simona@...ll.ch>, Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
	Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Philipp Zabel <p.zabel@...gutronix.de>, Geert Uytterhoeven <geert+renesas@...der.be>, 
	Magnus Damm <magnus.damm@...il.com>, dri-devel@...ts.freedesktop.org, 
	linux-renesas-soc@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, 
	Fabrizio Castro <fabrizio.castro.jz@...esas.com>, 
	Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: Re: [PATCH v5 04/12] drm: renesas: rz-du: mipi_dsi: Simplify HSFREQ calculation

Hi Laurent,

Thank you for the review.

On Tue, May 20, 2025 at 3:05 PM Laurent Pinchart
<laurent.pinchart@...asonboard.com> wrote:
>
> Hi Prabhakar,
>
> Thank you for the patch.
>
> On Mon, May 12, 2025 at 07:23:22PM +0100, Prabhakar wrote:
> > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> >
> > Simplify the high-speed clock frequency (HSFREQ) calculation by removing
> > the redundant multiplication and division by 8. The updated equation:
> >
> >     hsfreq = (mode->clock * bpp) / (dsi->lanes);
>
> You can drop the parentheses around the second factor. You can actuall
> drop all prentheses.
>
Agreed, I will drop the parentheses.

> >
> > produces the same result while improving readability and clarity.
> >
> > Additionally, update the comment to clarify the relationship between HS
> > clock bit frequency, HS byte clock frequency, and HSFREQ.
> >
> > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> > Reviewed-by: Biju Das <biju.das.jz@...renesas.com>
> > ---
> > v4->v5:
> > - No changes
> >
> > v3->v4:
> > - No changes
> >
> > v2->v3:
> > - No changes
> >
> > v1->v2:
> > - Added Reviewed-by tag from Biju
> > ---
> >  drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c b/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c
> > index ec8baecb9ba5..c5f698cd74f1 100644
> > --- a/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c
> > +++ b/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c
> > @@ -277,10 +277,10 @@ static int rzg2l_mipi_dsi_startup(struct rzg2l_mipi_dsi *dsi,
> >        *       hsclk: DSI HS Byte clock frequency (Hz)
> >        *       lanes: number of data lanes
> >        *
> > -      * hsclk(bit) = hsclk(byte) * 8
> > +      * hsclk(bit) = hsclk(byte) * 8 = hsfreq
> >        */
> >       bpp = mipi_dsi_pixel_format_to_bpp(dsi->format);
> > -     hsfreq = (mode->clock * bpp * 8) / (8 * dsi->lanes);
> > +     hsfreq = (mode->clock * bpp) / dsi->lanes;
>
> You can drop the parentheses here too.
>
OK, I'll drop the parentheses.

Cheers,
Prabhakar