[PATCH v5 08/12] drm: renesas: rz-du: mipi_dsi: Use mHz for D-PHY frequency calculations

[Prabhakar]

From: Lad Prabhakar <prabhakar.mahadev-lad.rj at bp.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 at renesas.com>
Signed-off-by: Fabrizio Castro <fabrizio.castro.jz at renesas.com>
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj at bp.renesas.com>
Reviewed-by: Biju Das <biju.das.jz at bp.renesas.com>
---
v4->v5:
- Added Reviewed tag from 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 5fc607be0c46..f93519613662 100644
--- a/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c
+++ b/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c
@@ -31,7 +31,7 @@
 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;
@@ -200,8 +200,9 @@ 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;
@@ -274,6 +275,7 @@ 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,
 	if (vclk_rate != mode->clock * MILLI)
 		dev_info(dsi->dev, "Requested vclk rate %lu, actual %lu mismatch\n",
 			 mode->clock * MILLI, vclk_rate);
-	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 at 60 with:
@@ -776,7 +779,7 @@ 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