[PATCH v2 3/4] dm: core: migrate debug() messages to use dm_warn

[Tom Rini]

On Wed, Oct 02, 2024 at 11:13:14AM -0400, Sean Anderson wrote:
> On 10/2/24 05:25, Quentin Schulz wrote:
> > Hi Alexander,
> > 
> > On 10/2/24 10:37 AM, Alexander Dahl wrote:
> > > Hello Quentin,
> > > 
> > > sorry for being late to the party, but I just tested v2024.10-rc6 and
> > > my console output looks like this now:
> > > 
> > >      ofnode_read_bool: bootph-all: true
> > >      ofnode_read_u32_array: ranges: ofnode_read_bool: bootph-all: false
> > >      ofnode_read_bool: bootph-some-ram: false
> > >      ofnode_read_bool: bootph-pre-ram: false
> > >      ofnode_read_bool: bootph-pre-sram: false
> > >      ofnode_read_bool: u-boot,dm-pre-reloc: false
> > >      ofnode_read_bool: u-boot,dm-pre-proper: false
> > >      ofnode_read_bool: u-boot,dm-spl: false
> > >      ofnode_read_bool: u-boot,dm-tpl: false
> > >      ofnode_read_bool: u-boot,dm-vpl: false
> > >      ofnode_read_bool: bootph-all: false
> > >      ofnode_read_bool: bootph-some-ram: false
> > >      ofnode_read_bool: bootph-pre-ram: false
> > >      ofnode_read_bool: bootph-pre-sram: false
> > >      ofnode_read_bool: u-boot,dm-pre-reloc: false
> > >      ofnode_read_bool: u-boot,dm-pre-proper: false
> > >      ofnode_read_bool: u-boot,dm-spl: false
> > >      ofnode_read_bool: u-boot,dm-tpl: false
> > >      ofnode_read_bool: u-boot,dm-vpl: false
> > >      ofnode_read_bool: bootph-all: true
> > >      ofnode_read_u32_array: ranges: ofnode_read_bool: bootph-all: true
> > >      ofnode_read_u32_array: ranges: ofnode_read_bool: bootph-all: true
> > >      ofnode_read_bool: bootph-all: true
> > >      ofnode_read_bool: bootph-all: false
> > >      …
> > > 
> > > This goes on for several screen pages, and clutters the usual output.
> > > I first thought I messed up CONFIG_LOGLEVEL or CONFIG_LOG, but no.
> > > All I had done was setting CONFIG_DM_WARN …
> > > 
> > > Am Tue, Jun 11, 2024 at 03:04:26PM +0200 schrieb Quentin Schulz:
> > > > From: Quentin Schulz <quentin.schulz at cherry.de>
> > > > 
> > > > Prior to that, seeing the debug() messages required to enable DM_DEBUG
> > > > which defines DEBUG (and then _DEBUG) which in turn makes failing
> > > > assert() calls reset U-Boot which isn't necessarily what is desired.
> > > > 
> > > > Instead, let's migrate to dm_warn which is using log_debug when unset or
> > > > log_warn when set.
> > > > 
> > > > While at it, reword the DM_DEBUG symbol in Kconfig to explain what it
> > > > now actually does.
> > > 
> > > CONFIG_DM_WARN currently reads like this:
> > > 
> > >      Enable this to see warnings related to driver model.
> > > 
> > >      Warnings may help with debugging, such as when expected devices do
> > >      not bind correctly. If the option is disabled, dm_warn() is compiled
> > >      out - it will do nothing when called.
> > > 
> > > Instead of just useful warnings, users get debug messages all over the
> > > place now.  Is this actually intended behaviour?  Can this be fixed
> > > before v2024.10 release please?
> > > 
> > 
> > There are basically less than 3 working days left before v2024.10 is released and I'm inclined to say this is annoying rather than a bug, so I am not entirely sure this will 1) make it in time if we agree on a fix (needs to include review process in those 3 working days) 2) be acceptable for a late addition in the release cycle. Let's try though, maybe we can figure something out.
> 
> This is a bug. Printing this many messages will have a major impact on boot times.
> 
> A config going from "may print out a few more lines of extra info" to "firehose"
> is very surprising to users (as evidenced by Alexander's email).
> 
> If you can't figure out which lines to disable, I recommend simply reverting the
> patch.

Checking this myself too, no platforms enable this by default. So I
believe we do need to improve the situation here, but I don't think we
need to revert this for release.

-- 
Tom
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