Messages in this thread | | | Subject | Re: [PATCH] clk: meson: Fix GXL HDMI PLL fractional bits width | From | Neil Armstrong <> | Date | Mon, 26 Nov 2018 16:13:24 +0100 |
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Hi Martin,
On 22/11/2018 23:05, Martin Blumenstingl wrote: > Hi Neil, > > On Thu, Nov 22, 2018 at 9:26 AM Neil Armstrong <narmstrong@baylibre.com> wrote: >> >> 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@baylibre.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. > I totally missed that - thanks for the explanation! > >>> >>> 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. > I'm curious: do you know whether the fractional divider field on > Meson8b is 10 or 12 bits wide? > > if you can add a short note about the naming confusion to the patch > description when applying the patch: > Acked-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
I'll add back the comments about the register shift and i'll apply it for a next PR.
Thanks, Neil
> > > Regards > Martin >
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