[PATCH 09/20] drm/bridge: tc358775: remove complex vsdelay calculation

From: Michael Walle
Date: Mon May 06 2024 - 09:38:40 EST


To cite the datasheet on VSDELAY:
During DSI link speed is slower than that of LVDS link’s, data needs
to be buffer within 775XBG before outputting to prevent data from
underflow. Register field VPCTRL[VSDELAY] is used to for this purpose

This driver assumes that the DSI link speed is the pixel clock (as does
every DSI bridge driver), after all the LVDS clock is derived from the
DSI clock. Thus we know for a fact, that the DSI link is not slower than
the LVDS side. Just use the (sane) default value of the bridge and drop
the complicated calculation here.

While at it, replace the TC358775_VPCTRL_MSF() and
TC358775_VPCTRL_OPXLFMT() inline functions by the usual macros for a bit
flag.

Signed-off-by: Michael Walle <mwalle@xxxxxxxxxx>
---
drivers/gpu/drm/bridge/tc358775.c | 49 +++++++--------------------------------
1 file changed, 8 insertions(+), 41 deletions(-)

diff --git a/drivers/gpu/drm/bridge/tc358775.c b/drivers/gpu/drm/bridge/tc358775.c
index 54aea58a3406..a9d731e87970 100644
--- a/drivers/gpu/drm/bridge/tc358775.c
+++ b/drivers/gpu/drm/bridge/tc358775.c
@@ -109,7 +109,9 @@
#define RDPKTLN 0x0404 /* Command Read Packet Length */

#define VPCTRL 0x0450 /* Video Path Control */
-#define EVTMODE BIT(5) /* Video event mode enable, tc35876x only */
+#define VPCTRL_MSF BIT(0)
+#define VPCTRL_OPXLFMT BIT(8)
+#define VPCTRL_EVTMODE BIT(5) /* Video event mode enable, tc35876x only */
#define HTIM1 0x0454 /* Horizontal Timing Control 1 */
#define HTIM2 0x0458 /* Horizontal Timing Control 2 */
#define VTIM1 0x045C /* Vertical Timing Control 1 */
@@ -187,30 +189,6 @@ enum {

#define L0EN BIT(1)

-#define TC358775_VPCTRL_VSDELAY__MASK 0x3FF00000
-#define TC358775_VPCTRL_VSDELAY__SHIFT 20
-static inline u32 TC358775_VPCTRL_VSDELAY(uint32_t val)
-{
- return ((val) << TC358775_VPCTRL_VSDELAY__SHIFT) &
- TC358775_VPCTRL_VSDELAY__MASK;
-}
-
-#define TC358775_VPCTRL_OPXLFMT__MASK 0x00000100
-#define TC358775_VPCTRL_OPXLFMT__SHIFT 8
-static inline u32 TC358775_VPCTRL_OPXLFMT(uint32_t val)
-{
- return ((val) << TC358775_VPCTRL_OPXLFMT__SHIFT) &
- TC358775_VPCTRL_OPXLFMT__MASK;
-}
-
-#define TC358775_VPCTRL_MSF__MASK 0x00000001
-#define TC358775_VPCTRL_MSF__SHIFT 0
-static inline u32 TC358775_VPCTRL_MSF(uint32_t val)
-{
- return ((val) << TC358775_VPCTRL_MSF__SHIFT) &
- TC358775_VPCTRL_MSF__MASK;
-}
-
#define TC358775_LVCFG_PCLKDIV__MASK 0x000000f0
#define TC358775_LVCFG_PCLKDIV__SHIFT 4
static inline u32 TC358775_LVCFG_PCLKDIV(uint32_t val)
@@ -350,7 +328,6 @@ static void tc_bridge_enable(struct drm_bridge *bridge)
u32 hback_porch, hsync_len, hfront_porch, hactive, htime1, htime2;
u32 vback_porch, vsync_len, vfront_porch, vactive, vtime1, vtime2;
unsigned int val = 0;
- u16 dsiclk, clkdiv, byteclk, t1, t2, t3, vsdelay;
struct drm_display_mode *mode;
struct drm_connector *connector = get_connector(bridge->encoder);

@@ -398,27 +375,17 @@ static void tc_bridge_enable(struct drm_bridge *bridge)

/* Video event mode vs pulse mode bit, does not exist for tc358775 */
if (tc->type == TC358765)
- val = EVTMODE;
+ val = VPCTRL_EVTMODE;
else
val = 0;

if (tc->bpc == 8)
- val |= TC358775_VPCTRL_OPXLFMT(1);
+ val |= VPCTRL_OPXLFMT;
else /* bpc = 6; */
- val |= TC358775_VPCTRL_MSF(1);
-
- dsiclk = mode->crtc_clock * 3 * tc->bpc / tc->num_dsi_lanes / 1000;
- clkdiv = dsiclk / (tc->lvds_link == DUAL_LINK ? DIVIDE_BY_6 : DIVIDE_BY_3);
- byteclk = dsiclk / 4;
- t1 = hactive * (tc->bpc * 3 / 8) / tc->num_dsi_lanes;
- t2 = ((100000 / clkdiv)) * (hactive + hback_porch + hsync_len + hfront_porch) / 1000;
- t3 = ((t2 * byteclk) / 100) - (hactive * (tc->bpc * 3 / 8) /
- tc->num_dsi_lanes);
-
- vsdelay = (clkdiv * (t1 + t3) / byteclk) - hback_porch - hsync_len - hactive;
+ val |= VPCTRL_MSF;

- val |= TC358775_VPCTRL_VSDELAY(vsdelay);
- regmap_write(tc->regmap, VPCTRL, val);
+ regmap_update_bits(tc->regmap, VPCTRL, val,
+ VPCTRL_OPXLFMT | VPCTRL_MSF | VPCTRL_EVTMODE);

regmap_write(tc->regmap, HTIM1, htime1);
regmap_write(tc->regmap, VTIM1, vtime1);

--
2.39.2