linux-kernel - RE: [PATCH v4 10/15] drm: renesas: rz-du: mipi_dsi: Use mHz for D-PHY frequency calculations

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Message-ID:
 <TY3PR01MB113460F756E0F38AD441C2229868F2@TY3PR01MB11346.jpnprd01.prod.outlook.com>
Date: Sun, 4 May 2025 12:51:27 +0000
From: Biju Das <biju.das.jz@...renesas.com>
To: Prabhakar <prabhakar.csengg@...il.com>, Andrzej Hajda
	<andrzej.hajda@...el.com>, Neil Armstrong <neil.armstrong@...aro.org>, Robert
 Foss <rfoss@...nel.org>, laurent.pinchart
	<laurent.pinchart@...asonboard.com>, Jonas Karlman <jonas@...boo.se>, Jernej
 Skrabec <jernej.skrabec@...il.com>, Maarten Lankhorst
	<maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>, Rob Herring <robh@...nel.org>, Krzysztof
 Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, Geert
 Uytterhoeven <geert+renesas@...der.be>, Michael Turquette
	<mturquette@...libre.com>, Stephen Boyd <sboyd@...nel.org>, Philipp Zabel
	<p.zabel@...gutronix.de>, Magnus Damm <magnus.damm@...il.com>
CC: "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-renesas-soc@...r.kernel.org" <linux-renesas-soc@...r.kernel.org>,
	"linux-clk@...r.kernel.org" <linux-clk@...r.kernel.org>, Fabrizio Castro
	<fabrizio.castro.jz@...esas.com>, Prabhakar Mahadev Lad
	<prabhakar.mahadev-lad.rj@...renesas.com>
Subject: RE: [PATCH v4 10/15] drm: renesas: rz-du: mipi_dsi: Use mHz for D-PHY
 frequency calculations

Hi Prabhakar,

Thanks for the patch.

> -----Original Message-----
> From: Prabhakar <prabhakar.csengg@...il.com>
> Sent: 30 April 2025 21:41
> Subject: [PATCH v4 10/15] drm: renesas: rz-du: mipi_dsi: Use mHz for D-PHY frequency calculations
> 
> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> 
> Pass the HSFREQ in milli-Hz to the `dphy_init()` callback to improve precision, especially for the
> RZ/V2H(P) SoC, where PLL dividers require high accuracy.
> 
> These changes prepare the driver for upcoming RZ/V2H(P) SoC support.
> 
> Co-developed-by: Fabrizio Castro <fabrizio.castro.jz@...esas.com>
> Signed-off-by: Fabrizio Castro <fabrizio.castro.jz@...esas.com>
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>

Reviewed-by: Biju Das <biju.das.jz@...renesas.com>

Cheers,
Biju

> ---
> v3->v4:
> - Used MILLI instead of KILO
> - Made use of mul_u32_u32() for multiplication
> 
> v2->v3:
> - Replaced `unsigned long long` with `u64`
> - Replaced *_mhz with *_millihz` in functions
> 
> v1->v2:
> - No changes
> ---
> ---
>  drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c | 13 ++++++++-----
>  1 file changed, 8 insertions(+), 5 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 ed259627f5e8..a4c0dbae4a46 100644
> --- a/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c
> +++ b/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c
> @@ -33,7 +33,7 @@
>  struct rzg2l_mipi_dsi;
> 
>  struct rzg2l_mipi_dsi_hw_info {
> -	int (*dphy_init)(struct rzg2l_mipi_dsi *dsi, unsigned long hsfreq);
> +	int (*dphy_init)(struct rzg2l_mipi_dsi *dsi, u64 hsfreq_millihz);
>  	void (*dphy_exit)(struct rzg2l_mipi_dsi *dsi);
>  	u32 phy_reg_offset;
>  	u32 link_reg_offset;
> @@ -203,8 +203,9 @@ static u32 rzg2l_mipi_dsi_link_read(struct rzg2l_mipi_dsi *dsi, u32 reg)
>   */
> 
>  static int rzg2l_mipi_dsi_dphy_init(struct rzg2l_mipi_dsi *dsi,
> -				    unsigned long hsfreq)
> +				    u64 hsfreq_millihz)
>  {
> +	unsigned long hsfreq = DIV_ROUND_CLOSEST_ULL(hsfreq_millihz, MILLI);
>  	const struct rzg2l_mipi_dsi_timings *dphy_timings;
>  	unsigned int i;
>  	u32 dphyctrl0;
> @@ -277,6 +278,7 @@ static int rzg2l_mipi_dsi_startup(struct rzg2l_mipi_dsi *dsi,
>  				  const struct drm_display_mode *mode)  {
>  	unsigned long hsfreq, vclk_rate;
> +	u64 hsfreq_millihz;
>  	unsigned int bpp;
>  	u32 txsetr;
>  	u32 clstptsetr;
> @@ -305,9 +307,9 @@ static int rzg2l_mipi_dsi_startup(struct rzg2l_mipi_dsi *dsi,
>  	 */
>  	bpp = mipi_dsi_pixel_format_to_bpp(dsi->format);
>  	vclk_rate = clk_get_rate(dsi->vclk);
> -	hsfreq = DIV_ROUND_CLOSEST_ULL(vclk_rate * bpp, dsi->lanes);
> +	hsfreq_millihz = DIV_ROUND_CLOSEST_ULL(mul_u32_u32(vclk_rate, bpp *
> +MILLI), dsi->lanes);
> 
> -	ret = dsi->info->dphy_init(dsi, hsfreq);
> +	ret = dsi->info->dphy_init(dsi, hsfreq_millihz);
>  	if (ret < 0)
>  		goto err_phy;
> 
> @@ -315,6 +317,7 @@ static int rzg2l_mipi_dsi_startup(struct rzg2l_mipi_dsi *dsi,
>  	txsetr = TXSETR_DLEN | TXSETR_NUMLANEUSE(dsi->lanes - 1) | TXSETR_CLEN;
>  	rzg2l_mipi_dsi_link_write(dsi, TXSETR, txsetr);
> 
> +	hsfreq = DIV_ROUND_CLOSEST_ULL(hsfreq_millihz, MILLI);
>  	/*
>  	 * Global timings characteristic depends on high speed Clock Frequency
>  	 * Currently MIPI DSI-IF just supports maximum FHD@60 with:
> @@ -778,7 +781,7 @@ static int rzg2l_mipi_dsi_probe(struct platform_device *pdev)
>  	 * mode->clock and format are not available. So initialize DPHY with
>  	 * timing parameters for 80Mbps.
>  	 */
> -	ret = dsi->info->dphy_init(dsi, 80000000);
> +	ret = dsi->info->dphy_init(dsi, 80000000ULL * MILLI);
>  	if (ret < 0)
>  		goto err_phy;
> 
> --
> 2.49.0