linux-kernel - Re: [PATCH v2 2/2] drm/bridge: anx7625: Add anx7625 MIPI DSI/DPI to DP bridge driver

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Date:   Thu, 10 Oct 2019 12:53:15 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Xin Ji <xji@...logixsemi.com>
Cc:     "devel@...verdev.osuosl.org" <devel@...verdev.osuosl.org>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Andrzej Hajda <a.hajda@...sung.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Nicolas Boichat <drinkcat@...omium.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        Sheng Pan <span@...logixsemi.com>
Subject: Re: [PATCH v2 2/2] drm/bridge: anx7625: Add anx7625 MIPI DSI/DPI to
 DP bridge driver

This code is *so* much nicer than before.  I hope you feel good about
the changes.  It makes me happy to look at this code now.

On Thu, Oct 10, 2019 at 09:34:19AM +0000, Xin Ji wrote:
> +static int edid_read(struct anx7625_data *ctx,
> +		     u8 offset, u8 *pblock_buf)
> +{
> +	int ret, cnt;
> +	struct device *dev = &ctx->client->dev;
> +
> +	for (cnt = 0; cnt < EDID_TRY_CNT; cnt++) {
> +		sp_tx_aux_wr(ctx, offset);
> +		/* set I2C read com 0x01 mot = 0 and read 16 bytes */
> +		ret = sp_tx_aux_rd(ctx, 0xf1);
> +
> +		if (ret) {
> +			sp_tx_rst_aux(ctx);
> +			DRM_DEV_DEBUG_DRIVER(dev, "edid read failed, reset!\n");
> +			cnt++;

I don't think you should increment cnt.  It's just a counter.

> +		} else {
> +			ret = anx7625_reg_block_read(ctx, ctx->i2c.rx_p0_client,
> +						     AP_AUX_BUFF_START,
> +						     MAX_DPCD_BUFFER_SIZE,
> +						     pblock_buf);
> +			if (!ret)
> +				break;
> +		}
> +	}
> +
> +	if (cnt == EDID_TRY_CNT)

And it could mean that "cnt > EDID_TRY_CNT".

> +		return -EIO;
> +
> +	return 0;
> +}
> +
> +static int segments_edid_read(struct anx7625_data *ctx,
> +			      u8 segment, u8 *buf, u8 offset)
> +{
> +	u8 cnt;
> +	int ret;
> +	struct device *dev = &ctx->client->dev;
> +
> +	/* write address only */
> +	ret = anx7625_reg_write(ctx, ctx->i2c.rx_p0_client,
> +				AP_AUX_ADDR_7_0, 0x30);
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p0_client,
> +				 AP_AUX_COMMAND, 0x04);
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p0_client,
> +				 AP_AUX_CTRL_STATUS,
> +				 AP_AUX_CTRL_ADDRONLY | AP_AUX_CTRL_OP_EN);
> +
> +	ret |= wait_aux_op_finish(ctx);
> +	/* write segment address */
> +	ret |= sp_tx_aux_wr(ctx, segment);
> +	/* data read */
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p0_client,
> +				 AP_AUX_ADDR_7_0, 0x50);
> +	if (ret) {
> +		DRM_ERROR("IO error : aux initial failed.\n");
> +		return ret;
> +	}
> +
> +	for (cnt = 0; cnt < EDID_TRY_CNT; cnt++) {
> +		sp_tx_aux_wr(ctx, offset);
> +		/* set I2C read com 0x01 mot = 0 and read 16 bytes */
> +		ret = sp_tx_aux_rd(ctx, 0xf1);
> +
> +		if (ret) {
> +			ret = sp_tx_rst_aux(ctx);
> +			DRM_DEV_ERROR(dev, "segment read failed, reset!\n");
> +			cnt++;

Same.

> +		} else {
> +			ret = anx7625_reg_block_read(ctx, ctx->i2c.rx_p0_client,
> +						     AP_AUX_BUFF_START,
> +						     MAX_DPCD_BUFFER_SIZE, buf);
> +			if (!ret)
> +				break;
> +		}
> +	}
> +
> +	if (cnt == EDID_TRY_CNT)
> +		return -EIO;
> +
> +	return 0;
> +}

regards,
dan carpenter