linux-kernel - Re: [PATCH 1/7] drm/rockchip: prepare common code for cdns and rk dpi/dp driver

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Date:   Tue, 2 Jun 2020 14:55:52 +0100
From:   Emil Velikov <emil.l.velikov@...il.com>
To:     sandor.yu@....com
Cc:     Andrzej Hajda <a.hajda@...sung.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        Heiko Stübner <heiko@...ech.de>,
        Sandy Huang <hjc@...k-chips.com>, dkos@...ence.com,
        ML dri-devel <dri-devel@...ts.freedesktop.org>,
        linux-rockchip <linux-rockchip@...ts.infradead.org>,
        "Linux-Kernel@...r. Kernel. Org" <linux-kernel@...r.kernel.org>,
        LAKML <linux-arm-kernel@...ts.infradead.org>,
        NXP Linux Team <linux-imx@....com>
Subject: Re: [PATCH 1/7] drm/rockchip: prepare common code for cdns and rk
 dpi/dp driver

HI Sandor Yu

On Mon, 1 Jun 2020 at 07:29, <sandor.yu@....com> wrote:
>
> From: Sandor Yu <Sandor.yu@....com>
>
> - Extracted common fields from cdn_dp_device to a new cdns_mhdp_device
>   structure which will be used by two separate drivers later on.
> - Moved some datatypes (audio_format, audio_info, vic_pxl_encoding_format,
>   video_info) from cdn-dp-core.c to cdn-dp-reg.h.
> - Changed prefixes from cdn_dp to cdns_mhdp
>     cdn -> cdns to match the other Cadence's drivers
>     dp -> mhdp to distinguish it from a "just a DP" as the IP underneath
>       this registers map can be a HDMI (which is internally different,
>       but the interface for commands, events is pretty much the same).
> - Modified cdn-dp-core.c to use the new driver structure and new function
>   names.
> - writel and readl are replaced by cdns_mhdp_bus_write and
>   cdns_mhdp_bus_read.
>
The high-level idea is great - split, refactor and reuse the existing drivers.

Although looking at the patches themselves - they seems to be doing
multiple things at once.
As indicated by the extensive list in the commit log.

I would suggest splitting those up a bit, roughly in line of the
itemisation as per the commit message.

Here is one hand wavy way to chunk this patch:
 1) use put_unalligned*
 2) 'use local variable dev' style of changes (as seem in cdn_dp_clk_enable)
 3) add writel/readl wrappers
 4) hookup struct cdns_mhdp_device, keep dp->mhdp detail internal.
The cdn-dp-reg.h function names/signatures will stay the same.
 5) finalize the helpers - use mhdp directly, rename

HTH
Emil

Examples:
4)
 static int cdn_dp_mailbox_read(struct cdn_dp_device *dp)
 {
+"  struct cdns_mhdp_device *mhdp = dp->mhdp;
   int val, ret;

-  ret = readx_poll_timeout(readl, dp->regs + MAILBOX_EMPTY_ADDR,
+  ret = readx_poll_timeout(readl, mhdp->regs_base + MAILBOX_EMPTY_ADDR,
...
   return fancy_readl(dp, MAILBOX0_RD_DATA) & 0xff;
 }

5)
-static int cdn_dp_mailbox_read(struct cdn_dp_device *dp)
+static int mhdp_mailbox_read(struct cdns_mhdp_device *mhdp)
 {
-  struct cdns_mhdp_device *mhdp = dp->mhdp;
   int val, ret;
...
-  return fancy_readl(dp, MAILBOX0_RD_DATA) & 0xff;
+  return cdns_mhdp_bus_read(mhdp, MAILBOX0_RD_DATA) & 0xff;
 }