linux-kernel - Re: [PATCH] clk: meson: Fix GXL HDMI PLL fractional bits width

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: <5e87ffda-4a38-f45b-00c4-6b73dc721656@baylibre.com>
Date:   Thu, 22 Nov 2018 09:26:21 +0100
From:   Neil Armstrong <narmstrong@...libre.com>
To:     Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Cc:     jbrunet@...libre.com, linux-amlogic@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] clk: meson: Fix GXL HDMI PLL fractional bits width

Hi Martin,

On 21/11/2018 22:53, Martin Blumenstingl wrote:
> Hi Neil,
> 
> On Wed, Nov 21, 2018 at 12:19 PM Neil Armstrong <narmstrong@...libre.com> wrote:
>>
>> The GXL Documentation specifies 12 bits for the Fractional bit field,
>> bit the last bits have a different purpose that we cannot handle right
>> now, so update the bitwidth to have correct fractional calculations.
> I assume you have more accurate documentation than what's available publicly:
> - the S805 datasheet doesn't have any documentation for this register at all
> - the S905 datasheet states that HHI_HDMI_PLL_CNTL2[11:0] are DIV_FRAC
> - the S905X and S912 datasheets state that SDMNC_POWER is at
> HHI_HDMI_PLL_CNTL2[6:0], SDMNC_ULMS is at HHI_HDMI_PLL_CNTL2[9:7] and
> SSC_DEP_SEL is at HHI_HDMI_PLL_CNTL2[13:10]
> - the S905X and S912 datasheets state that HHI_HDMI_PLL_CNTL1[11:0] are DIV_FRAC

On S905, the HHI_HDMI_PLL_CNTL2 is at address 0xc9 << 2, but on S905X/S905D/S912 the
equivalent register at same address is named HHI_HDMI_PLL_CNTL1.

They changed the numbering of registers between these 2 SoCs, but the register
content and addresses are similar for m/n/frac/reset.

> 
> can you confirm that the public S905X and S912 documentation is wrong
> and that the .frac field is really part of HHI_HDMI_PLL_CNTL2 instead
> of HHI_HDMI_PLL_CNTL1?

Is is part of HHI_HDMI_PLL_CNTL1 but at address of S905 HHI_HDMI_PLL_CNTL2.

When jerome pushed the PLL support earlier, he added a comment.
I simply forgot to put it back when I added back the GXL HDMI PLL DCO.

Neil

> 
> 
> Regards
> Martin
>