Re: [PATCH 2/2] drm/bridge: fsl-ldb: make warning message more informative

On 03/07/2025, Luca Ceresoli wrote:

Hello Liu,

Hello Luca,

thanks for your reviews.

On Fri, 7 Mar 2025 14:33:37 +0800
Liu Ying [off-list ref] wrote:

quoted

On 03/07/2025, Luca Ceresoli wrote:

quoted

This warning notifies a clock was set to an inaccurate value. Modify the
string to also show the clock name.

While doing that also rewrap the entire function call.

Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
---
 drivers/gpu/drm/bridge/fsl-ldb.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/bridge/fsl-ldb.c b/drivers/gpu/drm/bridge/fsl-ldb.c
index 0fc8a14fd80062248a43b8b93272101a7ca6158a..c7c899a9644bb827845fb3fe96a9695d79a91474 100644
--- a/drivers/gpu/drm/bridge/fsl-ldb.c
+++ b/drivers/gpu/drm/bridge/fsl-ldb.c

@@ -181,9 +181,9 @@ static void fsl_ldb_atomic_enable(struct drm_bridge *bridge,
 
 	configured_link_freq = clk_get_rate(fsl_ldb->clk);
 	if (configured_link_freq != requested_link_freq)
-		dev_warn(fsl_ldb->dev, "Configured LDB clock (%lu Hz) does not match requested LVDS clock: %lu Hz\n",
-			 configured_link_freq,
-			 requested_link_freq);
+		dev_warn(fsl_ldb->dev,
+			 "Configured %pC clock (%lu Hz) does not match requested LVDS clock: %lu Hz\n",
+			 fsl_ldb->clk, configured_link_freq, requested_link_freq);  

Though this slightly changes the warning message userspace sees, I guess it is
acceptable.

Does it make sense to s/%pC/%pCn/ so that the clock name is printed in lower
case instead of upper case, since it seems that all i.MX specific clock names
are in lower case?

%pC and %pCn print the same string, as I just discovered at
https://elixir.bootlin.com/linux/v6.14-rc5/source/lib/vsprintf.c#L1972

Ack.

I've pondering for a moment about whether we should document %pC and
%pCn produce the same output or rather %pCn. I decided to try the
latter and just sent a patch to do it [0].

FYI in my case the printed value is (with both %pC and %pCn)
"32ec0000.blk-ctrl:bridge@5c".

This is the LDB device name. The i.MX8MP LDB clock name is "media_ldb_root_clk".

Acked-by: Liu Ying <victor.liu@nxp.com>

[0] https://lore.kernel.org/20250307-vsprintf-pcn-v1-0-df0b2ccf610f@bootlin.com (local)

Luca

-- 
Regards,
Liu Ying