On Thu, 2021-10-28 at 12:42 +0100, Mauro Carvalho Chehab wrote: > Em Thu, 28 Oct 2021 18:34:47 +0900 > Tsuchiya Yuto <kitakar@xxxxxxxxx> escreveu: > > > <Adding back people/list to Cc> > > > > On Tue, 2021-10-26 at 09:32 +0100, Mauro Carvalho Chehab wrote: > > > Em Mon, 18 Oct 2021 01:19:54 +0900 > > > Tsuchiya Yuto <kitakar@xxxxxxxxx> escreveu: > > > > > > > (patch based on intel-aero kernel patch: > > > > https://github.com/intel-aero/meta-intel-aero-base/commit/26fc9fe5030b63bc9dcf0b5f32981948911ca272) > > > > > > > > Here is the original commit message from the aforementioned patch: > > > > > > > > From 26fc9fe5030b63bc9dcf0b5f32981948911ca272 Mon Sep 17 00:00:00 2001 > > > > From: Lucas De Marchi <lucas.demarchi@xxxxxxxxx> > > > > Date: Fri, 7 Jul 2017 14:23:53 -0700 > > > > Subject: [PATCH] linux-yocto: Remove remaining instance of call to > > > > trace_printk > > > > > > > > It's not sufficient to leave trace_printk() out of "normal call chains" since > > > > the way trace infrastructure works is that it will allocate the trace_printk > > > > buffers if the symbol is there (by using a separate section for the function > > > > and checking if __start_* and __stop_* symbols are different. > > > > > > > > Therefore, even if the default value for the param tells the module to use > > > > printk(), just the fact that it can be changed to trace_printk() means the > > > > initialization code will be called. > > > > > > > > The trace_printk() was replaced by pr_info() on commit 3d81099c75a6 > > > > ("media: atomisp: Replace trace_printk by pr_info") for the upstreamed > > > > atomisp, too. However, as the aforementioned commit message says, there > > > > is still a remaining instance. This causes the "trace_printk() being > > > > used" kernel warning message to still appear on the first driver load. > > > > > > > > Based on the aforementioned patch, this patch removes the call to > > > > ftrace_vprintk(). This removes that kernel warning. > > > > > > > > In addition to this, this patch also removes the following now unused > > > > things: > > > > > > > > - now empty atomisp_css2_dbg_ftrace_print() > > > > - trace_printk option from dbg_func kernel parameter > > > > > > This patch is incomplete. I mean, if the idea is to drop support for > > > trace, dbg_func parameter becomes obsolete, and a lot of code can be > > > dropped/cleaned. > > > > I left __set_css_print_env() and dbg_func module parameter intentionally > > because there is still the option "non", which means do not use any > > function to log. Yes, I don't know if it's really useful since the module > > parameter dbg_level=0 (this is the default value) means no debug output. > > > > However, they (those who originally wrote atomisp) added the option "non" > > anyway. So, I thought there is a use case for this. > > > > If everyone thinks it's useless, I can additionally remove them. In this > > case, indeed a lot of code may be additionally removed (I haven't checked > > yet). > > > > > That's said, I don't see a good reason to drop it, at least while > > > this driver is not 100%. > > > > This driver is not 100% yet, but at least it can capture images now > > (at least on ISP2401). So, I thought this is the right time to remove > > it when I wrote this patch. > > > > But yes, we don't necessarily have to drop it. The other idea is hide > > it by default using a macro, and still can be enabled by manual edit. > > Here is the example from drivers/usb/dwc2/core.h: > > > > 49-/* > > 50- * Suggested defines for tracers: > > 51- * - no_printk: Disable tracing > > 52- * - pr_info: Print this info to the console > > 53- * - trace_printk: Print this info to trace buffer (good for verbose logging) > > 54- */ > > 55- > > 56:#define DWC2_TRACE_SCHEDULER no_printk > > 57:#define DWC2_TRACE_SCHEDULER_VB no_printk > > 58- > > 59-/* Detailed scheduler tracing, but won't overwhelm console */ > > 60-#define dwc2_sch_dbg(hsotg, fmt, ...) \ > > 61: DWC2_TRACE_SCHEDULER(pr_fmt("%s: SCH: " fmt), \ > > 62- dev_name(hsotg->dev), ##__VA_ARGS__) > > 63- > > 64-/* Verbose scheduler tracing */ > > 65-#define dwc2_sch_vdbg(hsotg, fmt, ...) \ > > 66: DWC2_TRACE_SCHEDULER_VB(pr_fmt("%s: SCH: " fmt), \ > > 67- dev_name(hsotg->dev), ##__VA_ARGS__) > > > > with using pr_info by default for atomisp (the parameter dbg_level is > > 0 by default, so still no output by default). If this sounds OK, I'd > > like to try this way. > > Let's just postpone this change. It sounds a little early to start > cleaning up debug stuff. This can be done any time later, but let's > first test it on our devices and ensure that it is stable enough. Got it. First, let's focus on make atomisp work. But I still want to address this a little earlier after we made it work. That kernel warning message "trace_printk() being used" looks kinda scary...
