linux-kernel - Re: [PATCH v8] phy: mediatek: tphy: add debugfs files

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Date:   Thu, 16 Mar 2023 07:12:16 +0000
From:   Chunfeng Yun (云春峰) 
        <Chunfeng.Yun@...iatek.com>
To:     "vkoul@...nel.org" <vkoul@...nel.org>
CC:     "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "matthias.bgg@...il.com" <matthias.bgg@...il.com>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        "linux-phy@...ts.infradead.org" <linux-phy@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Eddie Hung (洪正鑫) 
        <Eddie.Hung@...iatek.com>
Subject: Re: [PATCH v8] phy: mediatek: tphy: add debugfs files

On Fri, 2023-02-10 at 21:01 +0530, Vinod Koul wrote:
> On 10-02-23, 16:58, Chunfeng Yun wrote:
> > These debugfs files are mainly used to make eye diagram test
> > easier,
> > especially helpful to do HQA test for a new IC without efuse
> > enabled.
> > 
> > Signed-off-by: Chunfeng Yun <chunfeng.yun@...iatek.com>
> > ---
> > v8: abandon patch to create phy debug root file
> >     /sys/kernel/debug/phy/ suggested by Vinod
> 
> Sorry that was not my suggestion
Sorry, I misunderstood you means
> 
> > 
> > v6~v7: no changes
> > 
> > v5: using common debugfs config CONFIG_DEBUG_FS
> > 
> > v4: fix build warning of sometimes uninitialized variable
> > 
> > v3: fix typo of "debugfs" suggested by AngeloGioacchino
> > 
> > v2: add CONFIG_PHY_MTK_TPHY_DEBUGFS suggested by AngeloGioacchino
> > ---
> >  drivers/phy/mediatek/phy-mtk-tphy.c | 405
> > +++++++++++++++++++++++++++-
> >  1 file changed, 404 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/phy/mediatek/phy-mtk-tphy.c
> > b/drivers/phy/mediatek/phy-mtk-tphy.c
> > index e906a82791bd..65a95c3726bf 100644
> > --- a/drivers/phy/mediatek/phy-mtk-tphy.c
> > +++ b/drivers/phy/mediatek/phy-mtk-tphy.c
> > @@ -7,6 +7,7 @@
> >  
> >  #include <dt-bindings/phy/phy.h>
> >  #include <linux/clk.h>
> > +#include <linux/debugfs.h>
> >  #include <linux/delay.h>
> >  #include <linux/iopoll.h>
> >  #include <linux/mfd/syscon.h>
> > @@ -264,6 +265,8 @@
> >  
> >  #define TPHY_CLKS_CNT	2
> >  
> > +#define USER_BUF_LEN(count) min_t(size_t, 8, (count))
> > +
> >  enum mtk_phy_version {
> >  	MTK_PHY_V1 = 1,
> >  	MTK_PHY_V2,
> > @@ -310,6 +313,7 @@ struct mtk_phy_instance {
> >  	struct clk_bulk_data clks[TPHY_CLKS_CNT];
> >  	u32 index;
> >  	u32 type;
> > +	struct dentry *dbgfs;
> >  	struct regmap *type_sw;
> >  	u32 type_sw_reg;
> >  	u32 type_sw_index;
> > @@ -332,10 +336,391 @@ struct mtk_tphy {
> >  	const struct mtk_phy_pdata *pdata;
> >  	struct mtk_phy_instance **phys;
> >  	int nphys;
> > +	struct dentry *dbgfs_root;
> >  	int src_ref_clk; /* MHZ, reference clock for slew rate
> > calibrate */
> >  	int src_coef; /* coefficient for slew rate calibrate */
> >  };
> 
> I asked the struct dentry *debugfs be part of struct phy. Debugfs
> would
> be created by core but rather than exported, it should be populated
> in
> phy and you can use it here in the driver
> 
> >  
Ok, I'll do the following steps:

0. put a struct dentry *debugfs in struct phy;
1. define a static struct dentry *phy_debugfs_root in phy-core.c, then
   create a root directory (/sys/kernel/debug/phy/) for phy subsystem 
in phy_core_init();
2. create directory for each phy under the root directory
(/sys/kernel/debug/phy/);
   this step has two ways:
   A: create the directory @debugfs of struct phy in phy_create() by
default;
   B: provide some api for user to create/destory the directory
@debugfs or others when need;
3. add private debugfs files in @debugfs of struct phy;

For the case in tphy driver, it provides some struct phy, the driver
may want to create debugfs files which not belongs to any struct phy in
the root directory (/sys/kernel/debug/phy/), then need provide a api.

   Do you have any suggestions?
   Which way do you prefer to use in step 2?

   Thanks a lot;

> <skip>
> > +
> >  static struct platform_driver mtk_tphy_driver = {
> >  	.probe		= mtk_tphy_probe,
> > +	.remove		= mtk_tphy_remove,
> >  	.driver		= {
> >  		.name	= "mtk-tphy",
> >  		.of_match_table = mtk_tphy_id_table,
> > -- 
> > 2.18.0
> 
>