Some registers can only be written indirectly, using DSI_CONFW register.
We don't have many uses for those registers (in fact, only DSI_CONTROL
is currently written), but the code to do those writes inline is a bit
confusing.

Add a new function, tc358768_confw_update_bits() which can be used to
write the bits indirectly. Only DSI_CONTROL is currently supported.

Signed-off-by: Tomi Valkeinen <[email protected]>
---
 drivers/gpu/drm/bridge/tc358768.c | 52 +++++++++++++++++++++++++++++----------
 1 file changed, 39 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/bridge/tc358768.c 
b/drivers/gpu/drm/bridge/tc358768.c
index dab9cdf5cb98..755ed6483b2e 100644
--- a/drivers/gpu/drm/bridge/tc358768.c
+++ b/drivers/gpu/drm/bridge/tc358768.c
@@ -123,7 +123,7 @@
 /* TC358768_DSI_CONFW (0x0500) register */
 #define TC358768_DSI_CONFW_MODE_SET    (5 << 29)
 #define TC358768_DSI_CONFW_MODE_CLR    (6 << 29)
-#define TC358768_DSI_CONFW_ADDR_DSI_CONTROL    (0x3 << 24)
+#define TC358768_DSI_CONFW_ADDR(x)     ((x) << 24)
 
 /* TC358768_DSICMD_TX (0x0600) register */
 #define TC358768_DSI_CMDTX_DC_START    BIT(0)
@@ -232,6 +232,36 @@ static void tc358768_update_bits(struct tc358768_priv 
*priv, u32 reg, u32 mask,
                tc358768_write(priv, reg, tmp);
 }
 
+static void tc358768_confw_update_bits(struct tc358768_priv *priv, u16 reg,
+                                      u16 mask, u16 val)
+{
+       u8 confw_addr;
+       u32 confw_val;
+
+       switch (reg) {
+       case TC358768_DSI_CONTROL:
+               confw_addr = 0x3;
+               break;
+       default:
+               priv->error = -EINVAL;
+               return;
+       }
+
+       if (mask != val) {
+               confw_val = TC358768_DSI_CONFW_MODE_CLR |
+                       TC358768_DSI_CONFW_ADDR(confw_addr) |
+                       mask;
+               tc358768_write(priv, TC358768_DSI_CONFW, confw_val);
+       }
+
+       if (val & mask) {
+               confw_val = TC358768_DSI_CONFW_MODE_SET |
+                       TC358768_DSI_CONFW_ADDR(confw_addr) |
+                       (val & mask);
+               tc358768_write(priv, TC358768_DSI_CONFW, confw_val);
+       }
+}
+
 static void tc358768_dsicmd_tx(struct tc358768_priv *priv)
 {
        u32 val;
@@ -693,7 +723,7 @@ static void tc358768_bridge_atomic_pre_enable(struct 
drm_bridge *bridge,
        struct tc358768_priv *priv = bridge_to_tc358768(bridge);
        struct mipi_dsi_device *dsi_dev = priv->output.dev;
        unsigned long mode_flags = dsi_dev->mode_flags;
-       u32 val, val2, lptxcnt, hact, data_type;
+       u32 val, mask, val2, lptxcnt, hact, data_type;
        s32 raw_val;
        struct drm_crtc_state *crtc_state;
        struct drm_connector_state *conn_state;
@@ -1065,13 +1095,7 @@ static void tc358768_bridge_atomic_pre_enable(struct 
drm_bridge *bridge,
        tc358768_write(priv, TC358768_DSI_START, 0x1);
 
        /* Configure DSI_Control register */
-       val = TC358768_DSI_CONFW_MODE_CLR | TC358768_DSI_CONFW_ADDR_DSI_CONTROL;
-       val |= TC358768_DSI_CONTROL_TXMD | TC358768_DSI_CONTROL_HSCKMD |
-              0x3 << 1 | TC358768_DSI_CONTROL_EOTDIS;
-       tc358768_write(priv, TC358768_DSI_CONFW, val);
-
-       val = TC358768_DSI_CONFW_MODE_SET | TC358768_DSI_CONFW_ADDR_DSI_CONTROL;
-       val |= (dsi_dev->lanes - 1) << 1;
+       val = (dsi_dev->lanes - 1) << 1;
 
        val |= TC358768_DSI_CONTROL_TXMD;
 
@@ -1081,11 +1105,13 @@ static void tc358768_bridge_atomic_pre_enable(struct 
drm_bridge *bridge,
        if (dsi_dev->mode_flags & MIPI_DSI_MODE_NO_EOT_PACKET)
                val |= TC358768_DSI_CONTROL_EOTDIS;
 
-       tc358768_write(priv, TC358768_DSI_CONFW, val);
+       mask = TC358768_DSI_CONTROL_TXMD | TC358768_DSI_CONTROL_HSCKMD |
+              0x3 << 1 | TC358768_DSI_CONTROL_EOTDIS;
+
+       tc358768_confw_update_bits(priv, TC358768_DSI_CONTROL, mask, val);
 
-       val = TC358768_DSI_CONFW_MODE_CLR | TC358768_DSI_CONFW_ADDR_DSI_CONTROL;
-       val |= TC358768_DSI_CONTROL_DSI_MODE;
-       tc358768_write(priv, TC358768_DSI_CONFW, val);
+       tc358768_confw_update_bits(priv, TC358768_DSI_CONTROL,
+                                  TC358768_DSI_CONTROL_DSI_MODE, 0);
 
        ret = tc358768_clear_error(priv);
        if (ret)

-- 
2.43.0

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