Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1273507

Re: [PATCH 01/25] serial: sh-sci: Update DT binding documentation for external clock input

From Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Newsgroups linux.kernel
Subject Re: [PATCH 01/25] serial: sh-sci: Update DT binding documentation for external clock input
Date 2015-11-19 22:20 +0100
Message-ID <qwEMx-6ku-9@gated-at.bofh.it> (permalink)
References <qwChI-4Cb-7@gated-at.bofh.it> <qwE0a-5Mi-3@gated-at.bofh.it> <qwEjv-5Tc-11@gated-at.bofh.it>
Organization linux.* mail to news gateway

Show all headers | View raw

Hi Geert,

On Thursday 19 November 2015 21:39:50 Geert Uytterhoeven wrote:
> On Thu, Nov 19, 2015 at 9:27 PM, Laurent Pinchart wrote:
> > On Thursday 19 November 2015 22:19:14 Laurent Pinchart wrote:
> >> On Thursday 19 November 2015 19:38:40 Geert Uytterhoeven wrote:
> >> > Amend the DT bindings to include the optional external clock on
> >> > (H)SCI(F) and some SCIFA, where this pin can serve as a clock input,
> >> > depending on board wiring.
> >> > 
> >> > --- a/Documentation/devicetree/bindings/serial/renesas,sci-serial.txt
> >> > +++ b/Documentation/devicetree/bindings/serial/renesas,sci-serial.txt
> >> > 
> >> > @@ -43,6 +43,9 @@ Required properties:
> >> >    - clocks: Must contain a phandle and clock-specifier pair for each
> >> >      entry in clock-names.
> >> >    - clock-names: Must contain "fck" for the SCIx UART functional
> >> >    clock.
> >> > +    On (H)SCI(F) and some SCIFA, an additional clock may be specified:
> >>
> >> Could you list the SCIFA variants that support external clocks ?
> >> 
> >> > +      - "hsck" for the optional external clock input (on HSCIF),
> >> > +      - "sck" for the optional external clock input (on other
> >> > variants).
> > 
> > Additionally, those clocks are used as inputs to the baud rate generator
> > for external clocks, as the ones listed in patch 02/25 in this series.
> > I'd merge the two patches and clarify the wording.
> 
> "SCK" predates the BRG, it even exists on SCI in H8/300.
> 
> That SCK is used as input to the BRG is just an artefact of how the BRG was
> added to the SCIF. The BRG is just muxed with the existing SCK to form a
> clock input, which is muxed with the BRR clock through the SCSCR.CKEx bits.
> And the BRG itself can choose between SCIF_CLK and INT_CLK.
> 
> Hence that's why I split it in two parts.

It makes sense with the explanation.

I think some of the patches should be clarified to mention BRG-EC (or whatever 
you want to call it) instead of just BRG, as otherwise it's very easy to 
confuse the two BRGs. The (H)SCK clock is an input to the internal BRG, while 
the SCIF_CLK and INT_CLK are inputs to the BRG-EC. Without clarification the 
DT bindings and the code can be hard to understand.

-- 
Regards,

Laurent Pinchart

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH 00/25] serial: sh-sci: Add external clock and BRG Support Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
  [PATCH 22/25] ARM: shmobile: koelsch dts: Enable SCIF_CLK frequency and pins Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
  [PATCH 16/25] serial: sh-sci: Correct SCIF type on RZ/A1H Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
  [PATCH 20/25] serial: sh-sci: Add support for optional BRG on (H)SCIF Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
  [PATCH 18/25] serial: sh-sci: Prepare for multiple clocks and baud rate generators Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
    Re: [PATCH 18/25] serial: sh-sci: Prepare for multiple clocks and baud rate generators Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-19 22:10 +0100
      Re: [PATCH 18/25] serial: sh-sci: Prepare for multiple clocks and  baud rate generators Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-20 09:00 +0100
        Re: [PATCH 18/25] serial: sh-sci: Prepare for multiple clocks and baud rate generators Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-20 15:50 +0100
          Re: [PATCH 18/25] serial: sh-sci: Prepare for multiple clocks and  baud rate generators Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-20 16:20 +0100
            Re: [PATCH 18/25] serial: sh-sci: Prepare for multiple clocks and baud rate generators Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-20 16:40 +0100
  [PATCH 05/25] serial: sh-sci: Drop unused frame_len parameter for sci_baud_calc_hscif() Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
  [PATCH 23/25] arm64: renesas: r8a7795 dtsi: Add BRG support for (H)SCIF Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
    Re: [PATCH 23/25] arm64: renesas: r8a7795 dtsi: Add BRG support for (H)SCIF Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-19 22:10 +0100
      Re: [PATCH 23/25] arm64: renesas: r8a7795 dtsi: Add BRG support for (H)SCIF Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-20 09:20 +0100
  [PATCH 02/25] serial: sh-sci: Update DT binding documentation for BRG support Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
    Re: [PATCH 02/25] serial: sh-sci: Update DT binding documentation for BRG support Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-19 21:30 +0100
      Re: [PATCH 02/25] serial: sh-sci: Update DT binding documentation for  BRG support Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-19 21:50 +0100
        Re: [PATCH 02/25] serial: sh-sci: Update DT binding documentation for BRG support Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-19 22:20 +0100
          Re: [PATCH 02/25] serial: sh-sci: Update DT binding documentation for  BRG support Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-20 09:00 +0100
  [PATCH 04/25] serial: sh-sci: Grammar s/Get ... for/Get ... from/ Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
  [PATCH 17/25] serial: sh-sci: Correct SCIF type on R-Car for BRG Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
    Re: [PATCH 17/25] serial: sh-sci: Correct SCIF type on R-Car for BRG Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-19 22:00 +0100
      Re: [PATCH 17/25] serial: sh-sci: Correct SCIF type on R-Car for BRG Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-20 08:50 +0100
        Re: [PATCH 17/25] serial: sh-sci: Correct SCIF type on R-Car for BRG Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-20 16:00 +0100
          Re: [PATCH 17/25] serial: sh-sci: Correct SCIF type on R-Car for BRG Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-20 16:40 +0100
          Re: [PATCH 17/25] serial: sh-sci: Correct SCIF type on R-Car for BRG Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-20 16:40 +0100
  [PATCH 06/25] serial: sh-sci: Don't overwrite clock selection in serial_console_write() Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
  [PATCH 13/25] serial: sh-sci: Take into account sampling rate for max baud rate Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
  [PATCH 21/25] ARM: shmobile: r8a7791 dtsi: Add BRG support for (H)SCIF Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
  [PATCH 14/25] serial: sh-sci: Add BRG register definitions Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
    Re: [PATCH 14/25] serial: sh-sci: Add BRG register definitions Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-19 21:50 +0100
  [PATCH 07/25] serial: sh-sci: Convert from clk_get() to devm_clk_get() Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
    Re: [PATCH 07/25] serial: sh-sci: Convert from clk_get() to devm_clk_get() Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-19 21:40 +0100
  [PATCH 01/25] serial: sh-sci: Update DT binding documentation for external clock input Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
    Re: [PATCH 01/25] serial: sh-sci: Update DT binding documentation for external clock input Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-19 21:20 +0100
      Re: [PATCH 01/25] serial: sh-sci: Update DT binding documentation for external clock input Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-19 21:30 +0100
        Re: [PATCH 01/25] serial: sh-sci: Update DT binding documentation for  external clock input Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-19 21:50 +0100
          Re: [PATCH 01/25] serial: sh-sci: Update DT binding documentation for external clock input Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-19 22:20 +0100
            Re: [PATCH 01/25] serial: sh-sci: Update DT binding documentation for  external clock input Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-20 09:10 +0100
      Re: [PATCH 01/25] serial: sh-sci: Update DT binding documentation for  external clock input Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-19 21:40 +0100
  [PATCH 03/25] serial: sh-sci: Drop useless check for zero sampling_rate Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
  [PATCH 24/25] arm64: renesas: salvator-x dts: Enable SCIF_CLK frequency and pins Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
  [PATCH 19/25] serial: sh-sci: Add support for optional external (H)SCK input Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
  [PATCH 11/25] serial: sh-sci: Avoid calculating the receive margin for HSCIF Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 20:00 +0100
  [PATCH 12/25] serial: sh-sci: Merge sci_scbrr_calc() and sci_baud_calc_hscif() Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 20:00 +0100
  [PATCH 10/25] serial: sh-sci: Improve bit rate error calculation for HSCIF Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 20:00 +0100
  Re: [PATCH 00/25] serial: sh-sci: Add external clock and BRG Support Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-19 22:10 +0100
    Re: [PATCH 00/25] serial: sh-sci: Add external clock and BRG Support Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-20 09:30 +0100
      Re: [PATCH 00/25] serial: sh-sci: Add external clock and BRG Support Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-20 10:00 +0100
        Re: [PATCH 00/25] serial: sh-sci: Add external clock and BRG Support Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-20 10:10 +0100
          Re: [PATCH 00/25] serial: sh-sci: Add external clock and BRG Support Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-20 16:00 +0100
            Re: [PATCH 00/25] serial: sh-sci: Add external clock and BRG Support Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-20 16:40 +0100
  Re: [PATCH 00/25] serial: sh-sci: Add external clock and BRG Support Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-20 10:10 +0100
  Re: [PATCH 00/25] serial: sh-sci: Add external clock and BRG Support Simon Horman <horms@verge.net.au> - 2015-11-24 03:50 +0100

csiph-web