linux-kernel - Re: [PATCH 2/2] memory: brcmstb_memc: Simplify compatible matching

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <52fb02f0-eef5-4bce-822e-140eb8769cd0@broadcom.com>
Date: Thu, 5 Jun 2025 14:15:46 -0700
From: Florian Fainelli <florian.fainelli@...adcom.com>
To: Krzysztof Kozlowski <krzk@...nel.org>, Rob Herring <robh@...nel.org>
Cc: linux-kernel@...r.kernel.org, justin.chen@...adcom.com,
 Conor Dooley <conor+dt@...nel.org>,
 Broadcom internal kernel review list
 <bcm-kernel-feedback-list@...adcom.com>,
 "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
 <devicetree@...r.kernel.org>,
 "moderated list:BROADCOM BCM7XXX ARM ARCHITECTURE"
 <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 2/2] memory: brcmstb_memc: Simplify compatible matching

On 6/5/25 13:30, Krzysztof Kozlowski wrote:
> On 05/06/2025 21:10, Florian Fainelli wrote:
>> On 6/5/25 11:55, Rob Herring wrote:
>>> On Fri, May 23, 2025 at 11:43:54AM -0700, Florian Fainelli wrote:
>>>> Now that a "brcm,brcmstb-memc-ddr-rev-b.2.x" fallback compatible string
>>>> has been defined, we can greatly simplify the matching within the driver
>>>> to only look for that compatible string and nothing else.
>>>>
>>>> The fallback "brcm,brcmstb-memc-ddr" is also updated to assume the V21
>>>> register layout since that is the most common nowadays.
>>>>
>>>> Signed-off-by: Florian Fainelli <florian.fainelli@...adcom.com>
>>>> ---
>>>>    drivers/memory/brcmstb_memc.c | 58 ++---------------------------------
>>>>    1 file changed, 3 insertions(+), 55 deletions(-)
>>>>
>>>> diff --git a/drivers/memory/brcmstb_memc.c b/drivers/memory/brcmstb_memc.c
>>>> index c87b37e2c1f0..ec4c198ddc49 100644
>>>> --- a/drivers/memory/brcmstb_memc.c
>>>> +++ b/drivers/memory/brcmstb_memc.c
>>>> @@ -181,65 +181,13 @@ static const struct of_device_id brcmstb_memc_of_match[] = {
>>>>    		.data = &brcmstb_memc_versions[BRCMSTB_MEMC_V20]
>>>>    	},
>>>>    	{
>>>> -		.compatible = "brcm,brcmstb-memc-ddr-rev-b.2.1",
>>>> +		.compatible = "brcm,brcmstb-memc-ddr-rev-b.2.x",
>>>>    		.data = &brcmstb_memc_versions[BRCMSTB_MEMC_V21]
>>>
>>> This entry is pointless because the default will get V21.
>>>
>>> In fact, I don't think you need the new compatible string at all. It
>>> doesn't work to add fallbacks after the fact.
>>
>> I agree and would prefer to keep adding new compatible strings which is
> 
> So you agree that adding such entries is pointless?

I don't think it is pointless, it's overly descriptive and we don't key 
off of it for now.

> 
>> what I initially did here:
>>
>> https://lore.kernel.org/all/20241217194439.929040-2-florian.fainelli@broadcom.com/
>>
>> but the feedback was that this should not be done, and hence this
>> attempt at defining a compatible string that would avoid needless churn.
>>
>> So which way should I go now?
> 
> And the advice was to use v2.1 fallback, not replace v2.1 with something
> else or keep adding pointless entries:
> https://lore.kernel.org/all/2e33t7ft5ermsfr7c4ympxrn6l5sqdef3wml4hlbnhdupoouwj@gfjpbmowjadi/

Fair enough then, I will re-spin accordingly. Thank you both.
-- 
Florian