RE: [RFC v1 PATCH 3/3] driver: update all the code that use soc_device_match

From: "Alice Guo (OSS)" <alice.guo@oss.nxp.com>
To: Dominique MARTINET <dominique.martinet@atmark-techno.com>,
	"Alice Guo (OSS)" <alice.guo@oss.nxp.com>
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Subject: RE: [RFC v1 PATCH 3/3] driver: update all the code that use soc_device_match
Date: Mon, 19 Apr 2021 07:09:35 +0000	[thread overview]
Message-ID: <AM6PR04MB6053B332D2FED8BD42C8642CE2499@AM6PR04MB6053.eurprd04.prod.outlook.com> (raw)
In-Reply-To: <YH0O907dfGY9jQRZ@atmark-techno.com>

> -----Original Message-----
> From: Dominique MARTINET <dominique.martinet@atmark-techno.com>
> Sent: 2021年4月19日 13:03
> To: Alice Guo (OSS) <alice.guo@oss.nxp.com>
> Subject: Re: [RFC v1 PATCH 3/3] driver: update all the code that use
> soc_device_match
> 
> Alice Guo (OSS) wrote on Mon, Apr 19, 2021 at 12:27:22PM +0800:
> > From: Alice Guo <alice.guo@nxp.com>
> >
> > Update all the code that use soc_device_match
> 
> A single patch might be difficult to accept for all components, a each maintainer
> will probably want to have a say on their subsystem?
> 
> I would suggest to split these for a non-RFC version; a this will really need to be
> case-by-case handling.
> 
> > because add support for soc_device_match returning -EPROBE_DEFER.
> 
> (English does not parse here for me)
> 
> I've only commented a couple of places in the code itself, but this doesn't seem
> to add much support for errors, just sweep the problem under the rug.
> 
> > Signed-off-by: Alice Guo <alice.guo@nxp.com>
> > ---
> >
> > diff --git a/drivers/bus/ti-sysc.c b/drivers/bus/ti-sysc.c index
> > 5fae60f8c135..00c59aa217c1 100644
> > --- a/drivers/bus/ti-sysc.c
> > +++ b/drivers/bus/ti-sysc.c
> > @@ -2909,7 +2909,7 @@ static int sysc_init_soc(struct sysc *ddata)
> >  	}
> >
> >  	match = soc_device_match(sysc_soc_feat_match);
> > -	if (!match)
> > +	if (!match || IS_ERR(match))
> >  		return 0;
> 
> This function handles errors, I would recommend returning the error as is if
> soc_device_match returned one so the probe can be retried later.
> 
> >
> >  	if (match->data)
> > diff --git a/drivers/clk/renesas/r8a7795-cpg-mssr.c
> > b/drivers/clk/renesas/r8a7795-cpg-mssr.c
> > index c32d2c678046..90a18336a4c3 100644
> > --- a/drivers/clk/renesas/r8a7795-cpg-mssr.c
> > +++ b/drivers/clk/renesas/r8a7795-cpg-mssr.c
> > @@ -439,6 +439,7 @@ static const unsigned int r8a7795es2_mod_nullify[]
> > __initconst = {
> >
> >  static int __init r8a7795_cpg_mssr_init(struct device *dev)  {
> > +	const struct soc_device_attribute *match;
> >  	const struct rcar_gen3_cpg_pll_config *cpg_pll_config;
> >  	u32 cpg_mode;
> >  	int error;
> > @@ -453,7 +454,8 @@ static int __init r8a7795_cpg_mssr_init(struct device
> *dev)
> >  		return -EINVAL;
> >  	}
> >
> > -	if (soc_device_match(r8a7795es1)) {
> > +	match = soc_device_match(r8a7795es1);
> > +	if (!IS_ERR(match) && match) {
> 
> Same, return the error.
> Assuming an error means no match will just lead to hard to debug problems
> because the driver potentially assumed the wrong device when it's just not
> ready yet.
> 
> >  		cpg_core_nullify_range(r8a7795_core_clks,
> >  				       ARRAY_SIZE(r8a7795_core_clks),
> >  				       R8A7795_CLK_S0D2, R8A7795_CLK_S0D12); [...]
> diff --git
> > a/drivers/iommu/ipmmu-vmsa.c b/drivers/iommu/ipmmu-vmsa.c index
> > eaaec0a55cc6..13a06b613379 100644
> > --- a/drivers/iommu/ipmmu-vmsa.c
> > +++ b/drivers/iommu/ipmmu-vmsa.c
> > @@ -757,17 +757,20 @@ static const char * const devices_allowlist[] =
> > {
> >
> >  static bool ipmmu_device_is_allowed(struct device *dev)  {
> > +	const struct soc_device_attribute *match1, *match2;
> >  	unsigned int i;
> >
> >  	/*
> >  	 * R-Car Gen3 and RZ/G2 use the allow list to opt-in devices.
> >  	 * For Other SoCs, this returns true anyway.
> >  	 */
> > -	if (!soc_device_match(soc_needs_opt_in))
> > +	match1 = soc_device_match(soc_needs_opt_in);
> > +	if (!IS_ERR(match1) && !match1)
> 
> I'm not sure what you intended to do, but !match1 already means there is no
> error so the original code is identical.
> 
> In this case ipmmu_device_is_allowed does not allow errors so this is one of the
> "difficult" drivers that require slightly more thinking.
> It is only called in ipmmu_of_xlate which does return errors properly, so in this
> case the most straightforward approach would be to make
> ipmmu_device_is_allowed return an int and forward errors as well.
> 

I will reconsider the existing problems. Thank you for your advice

> 
> ...
> This is going to need quite some more work to be acceptable, in my opinion, but
> I think it should be possible.
> 
> Thanks,
> --
> Dominique