Hi Andrew,

-----Original Message-----
From: Andrew Jeffery <redacted>
Sent: Tuesday, October 26, 2021 8:53 AM
Subject: Re: [PATCH 04/10] mmc: Add invert flag for clock phase signedness

On Wed, 22 Sep 2021, at 20:01, Chin-Ting Kuo wrote:

quoted

The clock phase degree may be between -360 to 360.
If the data signal is leading to the clock, the signedness of clock
phase is postive, otherwise, the signedness is negative.

Signed-off-by: Chin-Ting Kuo <chin-ting_kuo@aspeedtech.com>

The implementation here can't be changed without a change to the binding
documentation:

Okay, the binding document will be changed in the next patch version.

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Docume
ntation/devicetree/bindings/mmc/mmc-controller.yaml?h=v5.15-rc7#n345

quoted

---
 drivers/mmc/core/host.c  | 10 ++++++----  include/linux/mmc/host.h |
2 ++
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c index

d4683b1d263f..c2de7cbc7838 100644

--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c

@@ -214,14 +214,16 @@ static void mmc_retune_timer(struct timer_list

*t)  static void mmc_of_parse_timing_phase(struct device *dev, const char

*prop,

quoted

 				      struct mmc_clk_phase *phase)  {
-	int degrees[2] = {0};
+	int degrees[4] = {0};
 	int rc;

-	rc = device_property_read_u32_array(dev, prop, degrees, 2);
+	rc = device_property_read_u32_array(dev, prop, degrees, 4);
 	phase->valid = !rc;
 	if (phase->valid) {
-		phase->in_deg = degrees[0];
-		phase->out_deg = degrees[1];
+		phase->inv_in_deg = degrees[0] ? true : false;
+		phase->in_deg = degrees[1];
+		phase->inv_out_deg = degrees[2] ? true : false;
+		phase->out_deg = degrees[3];

This fundamentally breaks any in-tree users. We can't do this.

In terms of the binding, if negative phase values are something we must do,
we can just extend the value range to include [-359, -1] right?

Yes, agree it and I tried it before. But, it seems that the device tree doesn't support
negative value with "-" prefixed and there is no device tree related API used to get
the negative value from .dts. Thus, I tried to add an additional flag to present
negative value.

That avoids changing the type of the value positions in the manner this patch
does.

Andrew

Chin-Ting