Thread (3 messages) flat view 3 messages, 3 authors, 22d ago

Re: [PATCH net-next] dpll: zl3073x: add chip-specific minimum input reference frequency

From: Vincent Jardin <vjardin@free.fr>
Date: 2026-08-16 11:04:18
Also in: lkml

Hi Ivan,

Thanks for leading it. Below some few minor comments.
quoted hunk ↗ jump to hunk
diff --git a/drivers/dpll/zl3073x/core.c b/drivers/dpll/zl3073x/core.c
index 5b2d77f2c2288e..c0b3b0d579d524 100644
--- a/drivers/dpll/zl3073x/core.c
+++ b/drivers/dpll/zl3073x/core.c
@@ -20,29 +20,30 @@
 #include "dpll.h"
 #include "regs.h"
 
-#define ZL_CHIP_INFO(_id, _nchannels, _flags)				\
-	{ .id = (_id), .num_channels = (_nchannels), .flags = (_flags) }
+#define ZL_CHIP_INFO(_id, _nchannels, _flags, _min_freq)		\
+	{ .id = (_id), .num_channels = (_nchannels), .flags = (_flags),	\
+	  .min_ref_freq = (_min_freq) }
Do we really need this C macro ? Everytime we'll add something, it leads to a
wide numbder of line changes for zl3073x_chip_ids[]. What's about using directly the named
fields below and leaving 0/nothing for default cases such as the min_ref_freq ( something like
min_ref_freq ?: 1; ) ? 
 ... return zldev->info->min_ref_freq ?: 1; ...

If you prefer to keep the C macro, then let's use a variadic, something like:
#define ZL_CHIP_INFO(_id, _nchannels, _flags, ...)			\
	{ .id = (_id), .num_channels = (_nchannels), .flags = (_flags),\
	  ##__VA_ARGS__ }

then only the ZL30643 entry needs to be touched:
	ZL_CHIP_INFO(0x0E3B, 3, ZL3073X_FLAG_REF_PHASE_COMP_32,
		     .min_ref_freq = 1000),
 
 static const struct zl3073x_chip_info zl3073x_chip_ids[] = {
-	ZL_CHIP_INFO(0x0E30, 2, ZL3073X_FLAG_REF_PHASE_COMP_32),
-	ZL_CHIP_INFO(0x0E3B, 3, ZL3073X_FLAG_REF_PHASE_COMP_32),
 ...
-	ZL_CHIP_INFO(0x2E97, 5, ZL3073X_FLAG_DIE_TEMP),
-	ZL_CHIP_INFO(0x3FC4, 2, ZL3073X_FLAG_DIE_TEMP),
+	ZL_CHIP_INFO(0x0E30, 2, ZL3073X_FLAG_REF_PHASE_COMP_32, 1),
+	ZL_CHIP_INFO(0x0E3B, 3, ZL3073X_FLAG_REF_PHASE_COMP_32, 1000),
+	ZL_CHIP_INFO(0x0E93, 1, ZL3073X_FLAG_REF_PHASE_COMP_32, 1),
 ...
+	ZL_CHIP_INFO(0x2E97, 5, ZL3073X_FLAG_DIE_TEMP, 1),
+	ZL_CHIP_INFO(0x3FC4, 2, ZL3073X_FLAG_DIE_TEMP, 1),
That's a wide set of changes just to add/update 1 line. Since an update is needed, I feel the macro
should be avoided so only
	ZL_CHIP_INFO(0x0E3B, 3, ZL3073X_FLAG_REF_PHASE_COMP_32, 1000),
is needed.

Then, the init code could set to 1 if the value of .min_ref_freq is 0.
quoted hunk ↗ jump to hunk
--- a/drivers/dpll/zl3073x/dpll.c
+++ b/drivers/dpll/zl3073x/dpll.c
@@ -281,7 +281,8 @@ zl3073x_dpll_input_pin_ref_sync_set(const struct dpll_pin *dpll_pin,
 		sync_freq = zl3073x_ref_freq_get(sync_ref);
 
 		/* Sync signal must be 8 kHz or less and clock reference
-		 * must be 1 kHz or more and higher than the sync signal.
+		 * must meet the chip's minimum frequency requirement and be
+		 * higher than the sync signal.
 		 */
 		if (sync_freq > 8000) {
 			NL_SET_ERR_MSG(extack,
@@ -289,9 +290,10 @@ zl3073x_dpll_input_pin_ref_sync_set(const struct dpll_pin *dpll_pin,
 			rc = -EINVAL;
 			goto unlock;
 		}
-		if (ref_freq < 1000) {
-			NL_SET_ERR_MSG(extack,
-				       "clock frequency must be 1 kHz or more");
+		if (ref_freq < zldev->info->min_ref_freq) {
+			NL_SET_ERR_MSG_FMT(extack,
+					   "clock frequency must be %u Hz or more",
+					   zldev->info->min_ref_freq);
 			rc = -EINVAL;
 			goto unlock;
 		}
TBC: to be considered if 0 means 1 (à la zldev->info->min_ref_freq ?: 1)
quoted hunk ↗ jump to hunk
diff --git a/drivers/dpll/zl3073x/prop.c b/drivers/dpll/zl3073x/prop.c
index ac9d41d0f978ef..cdceddcf353e46 100644
--- a/drivers/dpll/zl3073x/prop.c
+++ b/drivers/dpll/zl3073x/prop.c
@@ -20,9 +20,9 @@
  * @freq: frequency to check
  *
  * The function checks the given frequency is valid for the device. For input
- * pins it checks that the frequency can be factorized using supported base
- * frequencies. For output pins it checks that the frequency divides connected
- * synth frequency without remainder.
+ * pins it checks that the frequency is above the chip's minimum and can be
+ * factorized using supported base frequencies. For output pins it checks that
+ * the frequency divides connected synth frequency without remainder.
  *
  * Return: true if the frequency is valid, false if not.
  */
@@ -36,6 +36,10 @@ zl3073x_pin_check_freq(struct zl3073x_dev *zldev, enum dpll_pin_direction dir,
 	if (dir == DPLL_PIN_DIRECTION_INPUT) {
 		int rc;
 
+		/* Check minimum frequency */
This comment is not needed, the code tells us.
+		if (freq < zldev->info->min_ref_freq)
+			goto err_inv_freq;
+
 		/* Check if the frequency can be factorized */
 		rc = zl3073x_ref_freq_factorize(freq, NULL, NULL);
 		if (rc)
Best regards,
  Vincent
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