linux-kernel - Re: [PATCH v2 06/26] drm/rockchip: dw-mipi-dsi: fix generic packet status check

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Message-ID: <5884500D.7070706@rock-chips.com>
Date:   Sun, 22 Jan 2017 14:24:13 +0800
From:   Chris Zhong <zyw@...k-chips.com>
To:     John Keeping <john@...anate.com>,
        Mark Yao <mark.yao@...k-chips.com>
Cc:     dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 06/26] drm/rockchip: dw-mipi-dsi: fix generic packet
 status check

Hi John

Reviewed-by: Chris Zhong <zyw@...k-chips.com>

On 01/22/2017 12:31 AM, John Keeping wrote:
> We want to check that both the GEN_CMD_EMPTY and GEN_PLD_W_EMPTY bits
> are set so we can't just check "val & mask" because that will be true if
> either bit is set.
According to DW mipi dsi controller databook, you are right. we should 
check both the 2 BIT.
gen_pld_w_empty:
This bit indicates the empty status of the generic write payload FIFO.
Dependency : DSI_GENERIC = 1. Otherwise, this bit is reserved.
Value after reset : 0x1

> Signed-off-by: John Keeping <john@...anate.com>
> ---
> Unchanged in v2
> ---
>   drivers/gpu/drm/rockchip/dw-mipi-dsi.c | 5 +++--
>   1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/rockchip/dw-mipi-dsi.c b/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
> index 4cbbbcb619b7..4be1ff3a42bb 100644
> --- a/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
> +++ b/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
> @@ -545,7 +545,7 @@ static int dw_mipi_dsi_host_detach(struct mipi_dsi_host *host,
>   static int dw_mipi_dsi_gen_pkt_hdr_write(struct dw_mipi_dsi *dsi, u32 hdr_val)
>   {
>   	int ret;
> -	u32 val;
> +	u32 val, mask;
>   
>   	ret = readx_poll_timeout(readl, dsi->base + DSI_CMD_PKT_STATUS,
>   				 val, !(val & GEN_CMD_FULL), 1000,
> @@ -557,8 +557,9 @@ static int dw_mipi_dsi_gen_pkt_hdr_write(struct dw_mipi_dsi *dsi, u32 hdr_val)
>   
>   	dsi_write(dsi, DSI_GEN_HDR, hdr_val);
>   
> +	mask = GEN_CMD_EMPTY | GEN_PLD_W_EMPTY;
>   	ret = readx_poll_timeout(readl, dsi->base + DSI_CMD_PKT_STATUS,
> -				 val, val & (GEN_CMD_EMPTY | GEN_PLD_W_EMPTY),
> +				 val, (val & mask) == mask,
>   				 1000, CMD_PKT_STATUS_TIMEOUT_US);
>   	if (ret < 0) {
>   		dev_err(dsi->dev, "failed to write command FIFO\n");