linux-kernel - Re: [PATCH v5 12/44] clk: davinci: Add platform information for TI DA850 PSC

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

Message-ID: <bb1f446e-5900-7e73-c1b7-955662a9541b@ti.com>
Date:   Wed, 17 Jan 2018 17:27:17 +0530
From:   Sekhar Nori <nsekhar@...com>
To:     David Lechner <david@...hnology.com>, <linux-clk@...r.kernel.org>,
        <devicetree@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>
CC:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...eaurora.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Kevin Hilman <khilman@...nel.org>,
        Adam Ford <aford173@...il.com>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 12/44] clk: davinci: Add platform information for TI
 DA850 PSC

On Tuesday 16 January 2018 10:51 PM, David Lechner wrote:
> On 01/16/2018 08:00 AM, Sekhar Nori wrote:
>> On Monday 08 January 2018 07:47 AM, David Lechner wrote:
>>> +void __init da850_psc_clk_init(void __iomem *psc0, void __iomem *psc1)
>>> +{
>>> +    struct clk_onecell_data *clk_data;
>>> +
>>> +    clk_data = davinci_psc_register_clocks(psc0, da850_psc0_info, 16);
>>> +    if (!clk_data)
>>> +        return;
>>> +
>>> +    clk_register_clkdev(clk_data->clks[3], NULL, "ti-aemif");
>>> +    clk_register_clkdev(clk_data->clks[3], "aemif", "davinci-nand.0");
>>> +    clk_register_clkdev(clk_data->clks[4], NULL, "spi_davinci.0");
>>> +    clk_register_clkdev(clk_data->clks[5], NULL, "da830-mmc.0");
>>> +    clk_register_clkdev(clk_data->clks[9], NULL, "serial8250.0");
>>> +    clk_register_clkdev(clk_data->clks[14], "arm", NULL);
>>> +    clk_register_clkdev(clk_data->clks[15], NULL, "davinci-rproc.0");
>>> +
>>> +    clk_free_onecell_data(clk_data);
>>> +
>>> +    clk_data = davinci_psc_register_clocks(psc1, da850_psc1_info, 32);
>>> +    if (!clk_data)
>>> +        return;
>>> +
>>> +    clk_register_clkdev(clk_data->clks[1], "usb20_psc_clk", NULL);
>>
>> Is this con_id really needed now? Searching for "usb20_psc_clk" in your
>> tree results in only this one hit.
> 
> Yes, this is left over from previous attempts.
> 
>>
>>> +    clk_register_clkdev(clk_data->clks[1], NULL, "musb-da8xx");
>>> +    clk_register_clkdev(clk_data->clks[1], NULL, "cppi41-dmaengine");
>>
>> I guess multiple dev_id matches like these are another hurdle in moving
>> them to davinci_psc_clk_info[] table? If its too cumbersome to keep
>> multiple entries in the table, they can be handled as an exception at
>> the end of processing the table? Still they are not the norm so I hope
>> the normal case will still benefit.
> 
> Right, as I mentioned in the reply to the previous patch, instead of
> assigning a con_id and dev_id to each clock, we would need to assign
> an array with a list of clocks. I think that would work better than
> trying to handle the extras as an exception since there, on average,
> about 5 per SoC.

Okay, are you going to try this to see how it looks? It looks like
samsung (clk-s3c2410.c) and tegra (clk-tegra20.c) use such tables
(although both use separate tables mapping just the gate number to
con_id/dev_id).

Others like u8540_clk.c and clk-mmp2.c have multiple calls in code to
clk_register_clkdev() like you have, but they keep them right after the
gate clock registration which makes it easy to see the mapping.

clk-imx35.c has multiple clk_register_clkdev() calls, but uses an enum
for the gates so its easy to see the mapping. This approach looks fine
to me as well.

So looks like there is a whole gamut of ways people have approached
this. But I do think we need to change the scheme you have currently
since it is difficult to review and audit (believe me on this one :))

Thanks,
Sekhar