linux-kernel - Re: [PATCH v2] memory: tegra: Add support for DBB clock on Tegra264

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <ac198371-fd2c-4f55-8fc2-2f3e18a88ccb@kernel.org>
Date: Sun, 18 Jan 2026 19:13:39 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Jon Hunter <jonathanh@...dia.com>,
 Thierry Reding <thierry.reding@...il.com>
Cc: linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] memory: tegra: Add support for DBB clock on Tegra264

On 16/01/2026 14:15, Jon Hunter wrote:
> 
> On 16/01/2026 12:37, Thierry Reding wrote:
>> From: Thierry Reding <treding@...dia.com>
>>
>> The DBB clock is needed by many IP blocks in order to access system
>> memory via the data backbone. The memory controller and external memory
>> controllers are the central place where these accesses are managed, so
>> make sure that the clock can be controlled from the corresponding
>> driver.
>>
>> Note that not all drivers fully register bandwidth requests, and hence
>> the EMC driver doesn't have enough information to know when it's safe to
>> switch the clock off, so for now it will be kept on permanently.
>>
>> Signed-off-by: Thierry Reding <treding@...dia.com>
>> ---
>> Changes in v2:
>> - convert to dev_err_probe() (Krzysztof)
>>
>>   drivers/memory/tegra/tegra186-emc.c | 8 ++++++++
>>   1 file changed, 8 insertions(+)
>>
>> diff --git a/drivers/memory/tegra/tegra186-emc.c b/drivers/memory/tegra/tegra186-emc.c
>> index dfddceecdd1a..03ebab6fbe68 100644
>> --- a/drivers/memory/tegra/tegra186-emc.c
>> +++ b/drivers/memory/tegra/tegra186-emc.c
>> @@ -22,6 +22,7 @@ struct tegra186_emc {
>>   	struct tegra_bpmp *bpmp;
>>   	struct device *dev;
>>   	struct clk *clk;
>> +	struct clk *clk_dbb;
>>   
>>   	struct tegra186_emc_dvfs *dvfs;
>>   	unsigned int num_dvfs;
>> @@ -328,6 +329,13 @@ static int tegra186_emc_probe(struct platform_device *pdev)
>>   		goto put_bpmp;
>>   	}
>>   
>> +	emc->clk_dbb = devm_clk_get_optional_enabled(&pdev->dev, "dbb");


This looks like new clock and I don't see it in the bindings. Are you
sure this is not an undocumented ABI? In case this was asked last time,
commit msg or changelog should briefly mention it, to avoid exactly that
question.

Best regards,
Krzysztof