linux-kernel - Re: [PATCH] drm/bridge: it6505: Add range and selector

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Message-ID: <c78389ca-ca0d-da13-7471-21aff6cc346c@intel.com>
Date:   Mon, 27 Mar 2023 10:32:57 +0200
From:   Andrzej Hajda <andrzej.hajda@...el.com>
To:     Hsin-Yi Wang <hsinyi@...omium.org>, Robert Foss <rfoss@...nel.org>,
        Douglas Anderson <dianders@...omium.org>
Cc:     xiazhengqiao <xiazhengqiao@...qin.corp-partner.google.com>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Jonas Karlman <jonas@...boo.se>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        kenneth.hung@....corp-partner.google.com
Subject: Re: [PATCH] drm/bridge: it6505: Add range and selector_reg

On 27.03.2023 06:48, Hsin-Yi Wang wrote:
> There are 2 banks on it6505, and when writing to different bank,
> REG_BANK_SEL needs to be set to the targeted bank. The current code set
> this additionally, which causes a race condition when a process is
> writing bank 0 registers while another process set the bank to 1. Set
> ranges in regmap config so the regmap API would handle the bank changes.
> 
> Signed-off-by: Hsin-Yi Wang <hsinyi@...omium.org>

Looks cool, especially comparing to locking patches.

Reviewed-by: Andrzej Hajda <andrzej.hajda@...el.com>

Regards
Andrzej

> ---
>   drivers/gpu/drm/bridge/ite-it6505.c | 34 +++++++++++++++++++----------
>   1 file changed, 23 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
> index bc451b2a77c28..abaf6e23775eb 100644
> --- a/drivers/gpu/drm/bridge/ite-it6505.c
> +++ b/drivers/gpu/drm/bridge/ite-it6505.c
> @@ -258,12 +258,12 @@
>   #define REG_AUD_INFOFRAM_SUM 0xFB
>   
>   /* the following six registers are in bank1 */
> -#define REG_DRV_0_DB_800_MV 0x7E
> -#define REG_PRE_0_DB_800_MV 0x7F
> -#define REG_PRE_3P5_DB_800_MV 0x81
> -#define REG_SSC_CTRL0 0x88
> -#define REG_SSC_CTRL1 0x89
> -#define REG_SSC_CTRL2 0x8A
> +#define REG_DRV_0_DB_800_MV 0x17E
> +#define REG_PRE_0_DB_800_MV 0x17F
> +#define REG_PRE_3P5_DB_800_MV 0x181
> +#define REG_SSC_CTRL0 0x188
> +#define REG_SSC_CTRL1 0x189
> +#define REG_SSC_CTRL2 0x18A
>   
>   #define RBR DP_LINK_BW_1_62
>   #define HBR DP_LINK_BW_2_7
> @@ -489,7 +489,7 @@ static const struct it6505_audio_sample_rate_map audio_sample_rate_map[] = {
>   };
>   
>   static const struct regmap_range it6505_bridge_volatile_ranges[] = {
> -	{ .range_min = 0, .range_max = 0xFF },
> +	{ .range_min = 0, .range_max = 0x1FF },
>   };
>   
>   static const struct regmap_access_table it6505_bridge_volatile_table = {
> @@ -497,11 +497,27 @@ static const struct regmap_access_table it6505_bridge_volatile_table = {
>   	.n_yes_ranges = ARRAY_SIZE(it6505_bridge_volatile_ranges),
>   };
>   
> +static const struct regmap_range_cfg it6505_regmap_banks[] = {
> +	{
> +		.name = "it6505",
> +		.range_min = 0x00,
> +		.range_max = 0x1FF,
> +		.selector_reg = REG_BANK_SEL,
> +		.selector_mask = 0x1,
> +		.selector_shift = 0,
> +		.window_start = 0x00,
> +		.window_len = 0x100,
> +	},
> +};
> +
>   static const struct regmap_config it6505_regmap_config = {
>   	.reg_bits = 8,
>   	.val_bits = 8,
>   	.volatile_table = &it6505_bridge_volatile_table,
>   	.cache_type = REGCACHE_NONE,
> +	.ranges = it6505_regmap_banks,
> +	.num_ranges = ARRAY_SIZE(it6505_regmap_banks),
> +	.max_register = 0x1FF,
>   };
>   
>   static int it6505_read(struct it6505 *it6505, unsigned int reg_addr)
> @@ -1267,7 +1283,6 @@ static void it6505_init(struct it6505 *it6505)
>   	it6505_write(it6505, REG_TIME_STMP_CTRL,
>   		     EN_SSC_GAT | EN_ENHANCE_VID_STMP | EN_ENHANCE_AUD_STMP);
>   	it6505_write(it6505, REG_INFOFRAME_CTRL, 0x00);
> -	it6505_write(it6505, REG_BANK_SEL, 0x01);
>   	it6505_write(it6505, REG_DRV_0_DB_800_MV,
>   		     afe_setting_table[it6505->afe_setting][0]);
>   	it6505_write(it6505, REG_PRE_0_DB_800_MV,
> @@ -1277,7 +1292,6 @@ static void it6505_init(struct it6505 *it6505)
>   	it6505_write(it6505, REG_SSC_CTRL0, 0x9E);
>   	it6505_write(it6505, REG_SSC_CTRL1, 0x1C);
>   	it6505_write(it6505, REG_SSC_CTRL2, 0x42);
> -	it6505_write(it6505, REG_BANK_SEL, 0x00);
>   }
>   
>   static void it6505_video_disable(struct it6505 *it6505)
> @@ -1506,11 +1520,9 @@ static void it6505_setup_ssc(struct it6505 *it6505)
>   	it6505_set_bits(it6505, REG_TRAIN_CTRL0, SPREAD_AMP_5,
>   			it6505->enable_ssc ? SPREAD_AMP_5 : 0x00);
>   	if (it6505->enable_ssc) {
> -		it6505_write(it6505, REG_BANK_SEL, 0x01);
>   		it6505_write(it6505, REG_SSC_CTRL0, 0x9E);
>   		it6505_write(it6505, REG_SSC_CTRL1, 0x1C);
>   		it6505_write(it6505, REG_SSC_CTRL2, 0x42);
> -		it6505_write(it6505, REG_BANK_SEL, 0x00);
>   		it6505_write(it6505, REG_SP_CTRL0, 0x07);
>   		it6505_write(it6505, REG_IP_CTRL1, 0x29);
>   		it6505_write(it6505, REG_IP_CTRL2, 0x03);