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Message-ID: <f4573a49-ae05-07bf-4e7c-70037b4596b9@intel.com>
Date: Fri, 24 Mar 2023 13:18:07 +0100
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: Neil Armstrong <neil.armstrong@...aro.org>,
Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
Jonas Karlman <jonas@...boo.se>,
Jernej Skrabec <jernej.skrabec@...il.com>,
David Airlie <airlied@...il.com>,
Daniel Vetter <daniel@...ll.ch>,
dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
kenneth.hung@....corp-partner.google.com,
xiazhengqiao <xiazhengqiao@...qin.corp-partner.google.com>
Subject: Re: [PATCH] drm/bridge: it6505: Add lock for it6505 i2c bank
On 24.03.2023 08:29, Hsin-Yi Wang wrote:
> From: xiazhengqiao <xiazhengqiao@...qin.corp-partner.google.com>
>
> When the i2c bank register (REG_BANK_SEL) is set to 1,
> only the registers belong to bank 1 can be written.
> There will be a race condition when a process is writing
> bank 0 registers while another process set the bank to 1.
> Add a mutex to handle regmap read/write locking for
> registers in multiple i2c bank. Since the driver now
> owns the lock, there's no need to use regmap API's lock.
>
> Signed-off-by: xiazhengqiao <xiazhengqiao@...qin.corp-partner.google.com>
> Signed-off-by: Hsin-Yi Wang <hsinyi@...omium.org>
> ---
> drivers/gpu/drm/bridge/ite-it6505.c | 72 ++++++++++++++++++++++-------
> 1 file changed, 55 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
> index bc451b2a77c28..1a8dcc49fc1ee 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
> @@ -414,12 +414,14 @@ struct it6505 {
> struct mutex extcon_lock;
> struct mutex mode_lock; /* used to bridge_detect */
> struct mutex aux_lock; /* used to aux data transfers */
> + struct mutex bank_lock; /* used to protect i2c bank access */
> struct regmap *regmap;
> struct drm_display_mode source_output_mode;
> struct drm_display_mode video_info;
> struct notifier_block event_nb;
> struct extcon_dev *extcon;
> struct work_struct extcon_wq;
> + int bank_state; /* 1 indicates bank 1, 0 indicates bank 0 */
> int extcon_state;
> enum drm_connector_status connector_status;
> enum link_train_status link_state;
> @@ -502,8 +504,22 @@ static const struct regmap_config it6505_regmap_config = {
> .val_bits = 8,
> .volatile_table = &it6505_bridge_volatile_table,
> .cache_type = REGCACHE_NONE,
> + .disable_locking = true,
> + .can_sleep = true,
> };
>
> +static int it6505_config_bank(struct it6505 *it6505, unsigned int reg_addr)
> +{
> + int err = 0, target = !!(reg_addr > 0xff);
> +
> + if (target != it6505->bank_state) {
It would be better to return if equal, this way you can avoid indentation.
> + err = regmap_write(it6505->regmap, REG_BANK_SEL, target);
> + if (!err)
> + it6505->bank_state = target;
> + }
> + return err;
> +}
> +
> static int it6505_read(struct it6505 *it6505, unsigned int reg_addr)
> {
> unsigned int value;
> @@ -513,7 +529,10 @@ static int it6505_read(struct it6505 *it6505, unsigned int reg_addr)
> if (!it6505->powered)
> return -ENODEV;
>
> - err = regmap_read(it6505->regmap, reg_addr, &value);
> + mutex_lock(&it6505->bank_lock);
> + err = it6505_config_bank(it6505, reg_addr);
> + err |= regmap_read(it6505->regmap, reg_addr & 0xff, &value);
Shoudn't be rather if (!err) err = regmap_read(...) ?
> + mutex_unlock(&it6505->bank_lock);
> if (err < 0) {
> dev_err(dev, "read failed reg[0x%x] err: %d", reg_addr, err);
> return err;
> @@ -531,8 +550,10 @@ static int it6505_write(struct it6505 *it6505, unsigned int reg_addr,
> if (!it6505->powered)
> return -ENODEV;
>
> - err = regmap_write(it6505->regmap, reg_addr, reg_val);
> -
> + mutex_lock(&it6505->bank_lock);
> + err = it6505_config_bank(it6505, reg_addr);
> + err |= regmap_write(it6505->regmap, reg_addr & 0xff, reg_val);
> + mutex_unlock(&it6505->bank_lock);
> if (err < 0) {
> dev_err(dev, "write failed reg[0x%x] = 0x%x err = %d",
> reg_addr, reg_val, err);
> @@ -551,7 +572,10 @@ static int it6505_set_bits(struct it6505 *it6505, unsigned int reg,
> if (!it6505->powered)
> return -ENODEV;
>
> - err = regmap_update_bits(it6505->regmap, reg, mask, value);
> + mutex_lock(&it6505->bank_lock);
> + err = it6505_config_bank(it6505, reg);
> + err |= regmap_update_bits(it6505->regmap, reg & 0xff, mask, value);
> + mutex_unlock(&it6505->bank_lock);
> if (err < 0) {
> dev_err(dev, "write reg[0x%x] = 0x%x mask = 0x%x failed err %d",
> reg, value, mask, err);
> @@ -892,7 +916,10 @@ static void it6505_aux_reset(struct it6505 *it6505)
>
> static void it6505_reset_logic(struct it6505 *it6505)
> {
> + mutex_lock(&it6505->bank_lock);
> + it6505_config_bank(it6505, REG_RESET_CTRL);
> regmap_write(it6505->regmap, REG_RESET_CTRL, ALL_LOGIC_RESET);
> + mutex_unlock(&it6505->bank_lock);
Why not call it6505_write ?
> usleep_range(1000, 1500);
> }
>
> @@ -972,9 +999,14 @@ static ssize_t it6505_aux_operation(struct it6505 *it6505,
> it6505_write(it6505, REG_AUX_ADR_16_19,
> ((address >> 16) & 0x0F) | ((size - 1) << 4));
>
> - if (cmd == CMD_AUX_NATIVE_WRITE)
> + if (cmd == CMD_AUX_NATIVE_WRITE) {
> + mutex_lock(&it6505->bank_lock);
> + it6505_config_bank(it6505, REG_AUX_OUT_DATA0);
> regmap_bulk_write(it6505->regmap, REG_AUX_OUT_DATA0, buffer,
> size);
> + mutex_unlock(&it6505->bank_lock);
> + }
> +
>
> /* Aux Fire */
> it6505_write(it6505, REG_AUX_CMD_REQ, cmd);
> @@ -1197,9 +1229,12 @@ static int it6505_send_video_infoframe(struct it6505 *it6505,
> if (err)
> return err;
>
> - err = regmap_bulk_write(it6505->regmap, REG_AVI_INFO_DB1,
> + mutex_lock(&it6505->bank_lock);
> + err = it6505_config_bank(it6505, REG_AVI_INFO_DB1);
> + err |= regmap_bulk_write(it6505->regmap, REG_AVI_INFO_DB1,
> buffer + HDMI_INFOFRAME_HEADER_SIZE,
> frame->length);
> + mutex_unlock(&it6505->bank_lock);
Common code with it6505_aux_operation, maybe it6505_bulk_write ?
Have you checked if regmap does not support banking? IMO it should be
implemented there.
Regards
Andrzej
> if (err)
> return err;
>
> @@ -1267,7 +1302,6 @@ 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 +1311,6 @@ 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 +1539,9 @@ 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);
> @@ -1983,8 +2014,11 @@ static int it6505_setup_sha1_input(struct it6505 *it6505, u8 *sha1_input)
> it6505_set_bits(it6505, REG_HDCP_CTRL2, HDCP_EN_M0_READ,
> HDCP_EN_M0_READ);
>
> - err = regmap_bulk_read(it6505->regmap, REG_M0_0_7,
> + mutex_lock(&it6505->bank_lock);
> + err = it6505_config_bank(it6505, REG_M0_0_7);
> + err |= regmap_bulk_read(it6505->regmap, REG_M0_0_7,
> sha1_input + msg_count, 8);
> + mutex_unlock(&it6505->bank_lock);
>
> it6505_set_bits(it6505, REG_HDCP_CTRL2, HDCP_EN_M0_READ, 0x00);
>
> @@ -2577,6 +2611,9 @@ static int it6505_poweron(struct it6505 *it6505)
> }
>
> it6505->powered = true;
> + mutex_lock(&it6505->bank_lock);
> + it6505->bank_state = 0;
> + mutex_unlock(&it6505->bank_lock);
> it6505_reset_logic(it6505);
> it6505_int_mask_enable(it6505);
> it6505_init(it6505);
> @@ -3359,6 +3396,7 @@ static int it6505_i2c_probe(struct i2c_client *client)
> mutex_init(&it6505->extcon_lock);
> mutex_init(&it6505->mode_lock);
> mutex_init(&it6505->aux_lock);
> + mutex_init(&it6505->bank_lock);
>
> it6505->bridge.of_node = client->dev.of_node;
> it6505->connector_status = connector_status_disconnected;
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