linux-kernel - RE: [PATCH 2/2] media: v4l: xilinx: Add Xilinx UHD-SDI Rx Subsystem driver

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Date:   Fri, 14 Jun 2019 12:15:24 +0000
From:   Vishal Sagar <vsagar@...inx.com>
To:     Joe Perches <joe@...ches.com>, Hyun Kwon <hyunk@...inx.com>,
        Vishal Sagar <vishal.sagar@...inx.com>
CC:     Hyun Kwon <hyunk@...inx.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Michal Simek <michals@...inx.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        Dinesh Kumar <dineshk@...inx.com>,
        Sandip Kothari <sandipk@...inx.com>
Subject: RE: [PATCH 2/2] media: v4l: xilinx: Add Xilinx UHD-SDI Rx Subsystem
 driver

Hi Joe,

Thanks for reviewing. 

> -----Original Message-----
> From: linux-media-owner@...r.kernel.org [mailto:linux-media-
> owner@...r.kernel.org] On Behalf Of Joe Perches
> Sent: Friday, June 14, 2019 4:02 AM
> To: Hyun Kwon <hyunk@...inx.com>; Vishal Sagar <vishal.sagar@...inx.com>
> Cc: Hyun Kwon <hyunk@...inx.com>; Laurent Pinchart
> <laurent.pinchart@...asonboard.com>; Mauro Carvalho Chehab
> <mchehab@...nel.org>; Michal Simek <michals@...inx.com>; Rob Herring
> <robh+dt@...nel.org>; Mark Rutland <mark.rutland@....com>; linux-
> kernel@...r.kernel.org; linux-media@...r.kernel.org; linux-arm-
> kernel@...ts.infradead.org; devicetree@...r.kernel.org; Dinesh Kumar
> <dineshk@...inx.com>; Sandip Kothari <sandipk@...inx.com>
> Subject: Re: [PATCH 2/2] media: v4l: xilinx: Add Xilinx UHD-SDI Rx Subsystem
> driver
> 
> EXTERNAL EMAIL
> 
> On Thu, 2019-06-13 at 15:05 -0700, Hyun Kwon wrote:
> > On Tue, 2019-06-04 at 06:55:56 -0700, Vishal Sagar wrote:
> 
> trivia:
> 
> > > diff --git a/drivers/media/platform/xilinx/xilinx-sdirxss.c
> b/drivers/media/platform/xilinx/xilinx-sdirxss.c
> []
> > > +static int xsdirx_get_stream_properties(struct xsdirxss_state *state)
> > > +{
> []
> > > +   if (valid & XSDIRX_ST352_VALID_DS1_MASK) {
> > > +           payload = xsdirxss_read(core, XSDIRX_ST352_DS1_REG);
> > > +           byte1 = (payload >> XST352_PAYLOAD_BYTE1_SHIFT) &
> > > +                           XST352_PAYLOAD_BYTE_MASK;
> 
> Is XST352_PAYLOAD_BYTE_MASK correct ?
> Should it be XST352_PAYLOAD_BYTE1_MASK ?
> 

I had thought of it to be a generic mask to extract a byte out of 4 bytes in a ST352 packet.
Hence named it as XST352_PAYLOAD_BYTE_MASK

> > > +           active_luma = (payload &
> XST352_BYTE3_ACT_LUMA_COUNT_MASK) >>
> > > +                           XST352_BYTE3_ACT_LUMA_COUNT_OFFSET;
> > > +           pic_type = (payload & XST352_BYTE2_PIC_TYPE_MASK) >>
> > > +                           XST352_BYTE2_PIC_TYPE_OFFSET;
> > > +           framerate = (payload >> XST352_BYTE2_FPS_SHIFT) &
> > > +                           XST352_BYTE2_FPS_MASK;
> > > +           tscan = (payload & XST352_BYTE2_TS_TYPE_MASK) >>
> > > +                           XST352_BYTE2_TS_TYPE_OFFSET;
> >
> > Please align consistently throughout the patch. I believe the checkpatch
> > --strict warns on these.
> 
> I believe not.
> 
> Another possibility would be to use a macro like:
> 
> #define mask_and_shift(val, type)       \
>         ((val) & (XST352_ ## type ## _MASK)) >> (XST352_ ## type ## _OFFSET))
> 
> > > +           sampling = (payload & XST352_BYTE3_COLOR_FORMAT_MASK) >>
> > > +                      XST352_BYTE3_COLOR_FORMAT_OFFSET;
> 
> So these could be something like:
> 
>                 sampling = mask_and_shift(payload, BYTE3_COLOR_FORMAT);
> 

This looks like a good way. I will modify this in v2. 
I will also modify the XST352_PAYLOAD_BYTE_MASK to 
XST352_PAYLOAD_BYTE1_MASK so that this aligns with the macro.

Regards
Vishal Sagar