[PATCH v2 2/3] media: ccs-pll: Support optional input for VT pixel rate

[Jai Luthra <jai.luthra@ideasonboard.com>]

When the PLL is configured in DUAL_MODE (separate VT and OP trees) and
the sensor's FIFOs allow derating and/or overrating, the VT pixel rate
might be higher or lower than OP pixel rate.

Support such usecases by allowing an optional input for the target VT
pixel rate.

Signed-off-by: Jai Luthra <jai.luthra@ideasonboard.com>
---
 drivers/media/i2c/ccs-pll.c | 13 +++++++++++--
 drivers/media/i2c/ccs-pll.h |  4 +++-
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/drivers/media/i2c/ccs-pll.c b/drivers/media/i2c/ccs-pll.c
index 1605cfa5db19..9aa164994cc7 100644
--- a/drivers/media/i2c/ccs-pll.c
+++ b/drivers/media/i2c/ccs-pll.c
@@ -388,6 +388,14 @@ __ccs_pll_calculate_vt_tree(struct device *dev,
 	return 0;
 }
 
+static inline u32 ccs_pll_vt_pixel_rate(const struct ccs_pll *pll)
+{
+	if (pll->pixel_rate_pixel_array)
+		return pll->pixel_rate_pixel_array;
+
+	return pll->pixel_rate_csi;
+}
+
 static int ccs_pll_calculate_vt_tree(struct device *dev,
 				     const struct ccs_pll_limits *lim,
 				     struct ccs_pll *pll)
@@ -396,11 +404,12 @@ static int ccs_pll_calculate_vt_tree(struct device *dev,
 	struct ccs_pll_branch_fr *pll_fr = &pll->vt_fr;
 	u16 min_pre_pll_clk_div = lim_fr->min_pre_pll_clk_div;
 	u16 max_pre_pll_clk_div = lim_fr->max_pre_pll_clk_div;
+	u32 vt_pixel_rate = ccs_pll_vt_pixel_rate(pll);
 	u32 pre_mul, pre_div;
 
-	pre_div = gcd(pll->pixel_rate_csi,
+	pre_div = gcd(vt_pixel_rate,
 		      pll->ext_clk_freq_hz * pll->vt_lanes);
-	pre_mul = pll->pixel_rate_csi / pre_div;
+	pre_mul = vt_pixel_rate / pre_div;
 	pre_div = pll->ext_clk_freq_hz * pll->vt_lanes / pre_div;
 
 	/* Make sure PLL input frequency is within limits */
diff --git a/drivers/media/i2c/ccs-pll.h b/drivers/media/i2c/ccs-pll.h
index e22903931e72..5c00a72c41df 100644
--- a/drivers/media/i2c/ccs-pll.h
+++ b/drivers/media/i2c/ccs-pll.h
@@ -114,7 +114,9 @@ struct ccs_pll_branch_bk {
  * @op_bk: Operational timing back-end configuration (output)
  * @pixel_rate_csi: Pixel rate on the output data bus (output)
  * @pixel_rate_pixel_array: Nominal pixel rate in the sensor's pixel array
- *			    (output)
+ *			    (input/output). It is a valid input only when
+ *			    FLAG_DUAL_PLL is set, serving as a target rate
+ *			    for the VT tree.
  */
 struct ccs_pll {
 	/* input values */

-- 
2.54.0