Re: [PATCH] optee: simplify i2c access

On 25/01/21, Arnd Bergmann wrote:

From: Arnd Bergmann arnd@arndb.de

Storing a bogus i2c_client structure on the stack adds overhead and causes a compile-time warning:

drivers/tee/optee/rpc.c:493:6: error: stack frame size of 1056 bytes in function 'optee_handle_rpc' [-Werror,-Wframe-larger-than=] void optee_handle_rpc(struct tee_context *ctx, struct optee_rpc_param *param,

Change the implementation of handle_rpc_func_cmd_i2c_transfer() to open-code the i2c_transfer() call, which makes it easier to read and avoids the warning.

Fixes: c05210ab9757 ("drivers: optee: allow op-tee to access devices on the i2c bus")

does fixing stack-frame compile warnings need a 'fixes' tag?

Signed-off-by: Arnd Bergmann arnd@arndb.de

drivers/tee/optee/rpc.c | 31 ++++++++++++++++--------------- 1 file changed, 16 insertions(+), 15 deletions(-)

diff --git a/drivers/tee/optee/rpc.c b/drivers/tee/optee/rpc.c index 1e3614e4798f..6cbb3643c6c4 100644 --- a/drivers/tee/optee/rpc.c +++ b/drivers/tee/optee/rpc.c @@ -54,8 +54,9 @@ static void handle_rpc_func_cmd_get_time(struct optee_msg_arg *arg) static void handle_rpc_func_cmd_i2c_transfer(struct tee_context *ctx, struct optee_msg_arg *arg) {

• struct i2c_client client = { 0 }; struct tee_param *params;

• struct i2c_adapter *adapter;
• struct i2c_msg msg = { }; size_t i; int ret = -EOPNOTSUPP; u8 attr[] = {

@@ -85,48 +86,48 @@ static void handle_rpc_func_cmd_i2c_transfer(struct tee_context *ctx, goto bad; }

• client.adapter = i2c_get_adapter(params[0].u.value.b);
• if (!client.adapter)

• adapter = i2c_get_adapter(params[0].u.value.b);
• if (!adapter) goto bad;

if (params[1].u.value.a & OPTEE_MSG_RPC_CMD_I2C_FLAGS_TEN_BIT) {

• if (!i2c_check_functionality(client.adapter,
  

• if (!i2c_check_functionality(adapter,
  		     I2C_FUNC_10BIT_ADDR)) {
  

• 	i2c_put_adapter(client.adapter);
  

• 	i2c_put_adapter(adapter);
  goto bad;
  

  }

• client.flags = I2C_CLIENT_TEN;
  

• msg.flags = I2C_M_TEN;
  

  }

• client.addr = params[0].u.value.c;
• snprintf(client.name, I2C_NAME_SIZE, "i2c%d", client.adapter->nr);

• msg.addr = params[0].u.value.c;
• msg.buf = params[2].u.memref.shm->kaddr;
• msg.len = params[2].u.memref.size;

switch (params[0].u.value.a) { case OPTEE_MSG_RPC_CMD_I2C_TRANSFER_RD:

• ret = i2c_master_recv(&client, params[2].u.memref.shm->kaddr,
  

• 		      params[2].u.memref.size);
  

• msg.flags |= I2C_M_RD;
  

  break; case OPTEE_MSG_RPC_CMD_I2C_TRANSFER_WR:

• ret = i2c_master_send(&client, params[2].u.memref.shm->kaddr,
  

• 		      params[2].u.memref.size);
  

  break; default:

• i2c_put_adapter(client.adapter);
  

• i2c_put_adapter(adapter);
  

  goto bad; }

• ret = i2c_transfer(adapter, &msg, 1);
• if (ret < 0) { arg->ret = TEEC_ERROR_COMMUNICATION; } else {

• params[3].u.value.a = ret;
  

• params[3].u.value.a = msg.len;
  

  if (optee_to_msg_param(arg->params, arg->num_params, params)) arg->ret = TEEC_ERROR_BAD_PARAMETERS; else arg->ret = TEEC_SUCCESS; }

• i2c_put_adapter(client.adapter);

• i2c_put_adapter(adapter); kfree(params); return;

bad:

2.29.2