linux-kernel - [PATCH v2 2/9] media: i2c: ds90ub960: Replace aliased clients list with bitmap

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Message-Id: <20241118-fpc202-v2-2-744e4f192a2d@bootlin.com>
Date: Mon, 18 Nov 2024 11:13:01 +0100
From: Romain Gantois <romain.gantois@...tlin.com>
To: Wolfram Sang <wsa+renesas@...g-engineering.com>, 
 Tomi Valkeinen <tomi.valkeinen@...asonboard.com>, 
 Luca Ceresoli <luca.ceresoli@...tlin.com>, 
 Andi Shyti <andi.shyti@...nel.org>, Rob Herring <robh@...nel.org>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, Derek Kiernan <derek.kiernan@....com>, 
 Dragan Cvetic <dragan.cvetic@....com>, Arnd Bergmann <arnd@...db.de>, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 Mauro Carvalho Chehab <mchehab@...nel.org>, 
 Linus Walleij <linus.walleij@...aro.org>, 
 Bartosz Golaszewski <brgl@...ev.pl>
Cc: Thomas Petazzoni <thomas.petazzoni@...tlin.com>, 
 Kory Maincent <kory.maincent@...tlin.com>, linux-i2c@...r.kernel.org, 
 linux-kernel@...r.kernel.org, devicetree@...r.kernel.org, 
 linux-media@...r.kernel.org, linux-gpio@...r.kernel.org, 
 Romain Gantois <romain.gantois@...tlin.com>
Subject: [PATCH v2 2/9] media: i2c: ds90ub960: Replace aliased clients list
 with bitmap

The ds90ub960 driver currently uses a list of i2c_client structs to keep
track of used I2C address translator (ATR) alias slots for each RX port.

Keeping these i2c_client structs in the alias slot list isn't actually
needed, the driver only needs to know if a specific alias slot is already
in use or not.

Convert the aliased_clients list to a bitmap named "alias_use_mask". This
will allow removing the "client" parameter from the i2c-atr callbacks in a
future patch.

Signed-off-by: Romain Gantois <romain.gantois@...tlin.com>
---
 drivers/media/i2c/ds90ub960.c | 23 +++++++++--------------
 1 file changed, 9 insertions(+), 14 deletions(-)

diff --git a/drivers/media/i2c/ds90ub960.c b/drivers/media/i2c/ds90ub960.c
index ffe5f25f8647624be005da33a6412da2493413b4..f86028894c78187257efc8fd70812387000796f7 100644
--- a/drivers/media/i2c/ds90ub960.c
+++ b/drivers/media/i2c/ds90ub960.c
@@ -468,7 +468,7 @@ struct ub960_rxport {
 		};
 	} eq;
 
-	const struct i2c_client *aliased_clients[UB960_MAX_PORT_ALIASES];
+	DECLARE_BITMAP(alias_use_mask, UB960_MAX_PORT_ALIASES);
 };
 
 struct ub960_asd {
@@ -1032,17 +1032,13 @@ static int ub960_atr_attach_client(struct i2c_atr *atr, u32 chan_id,
 	struct device *dev = &priv->client->dev;
 	unsigned int reg_idx;
 
-	for (reg_idx = 0; reg_idx < ARRAY_SIZE(rxport->aliased_clients); reg_idx++) {
-		if (!rxport->aliased_clients[reg_idx])
-			break;
-	}
-
-	if (reg_idx == ARRAY_SIZE(rxport->aliased_clients)) {
+	reg_idx = find_first_zero_bit(rxport->alias_use_mask, UB960_MAX_PORT_ALIASES);
+	if (reg_idx >= UB960_MAX_PORT_ALIASES) {
 		dev_err(dev, "rx%u: alias pool exhausted\n", rxport->nport);
 		return -EADDRNOTAVAIL;
 	}
 
-	rxport->aliased_clients[reg_idx] = client;
+	set_bit(reg_idx, rxport->alias_use_mask);
 
 	ub960_rxport_write(priv, chan_id, UB960_RR_SLAVE_ID(reg_idx),
 			   client->addr << 1);
@@ -1063,18 +1059,15 @@ static void ub960_atr_detach_client(struct i2c_atr *atr, u32 chan_id,
 	struct device *dev = &priv->client->dev;
 	unsigned int reg_idx;
 
-	for (reg_idx = 0; reg_idx < ARRAY_SIZE(rxport->aliased_clients); reg_idx++) {
-		if (rxport->aliased_clients[reg_idx] == client)
-			break;
-	}
+	reg_idx = find_first_zero_bit(rxport->alias_use_mask, UB960_MAX_PORT_ALIASES);
 
-	if (reg_idx == ARRAY_SIZE(rxport->aliased_clients)) {
+	if (reg_idx >= UB960_MAX_PORT_ALIASES) {
 		dev_err(dev, "rx%u: client 0x%02x is not mapped!\n",
 			rxport->nport, client->addr);
 		return;
 	}
 
-	rxport->aliased_clients[reg_idx] = NULL;
+	clear_bit(reg_idx, rxport->alias_use_mask);
 
 	ub960_rxport_write(priv, chan_id, UB960_RR_SLAVE_ALIAS(reg_idx), 0);
 
@@ -3404,6 +3397,8 @@ static int ub960_parse_dt_rxport(struct ub960_data *priv, unsigned int nport,
 	if (ret)
 		goto err_put_remote_fwnode;
 
+	bitmap_zero(rxport->alias_use_mask, UB960_MAX_PORT_ALIASES);
+
 	return 0;
 
 err_put_remote_fwnode:

-- 
2.47.0