Re: [PATCH] drivers: optee: i2c: add bus retry configuration

Jorge Ramirez-Ortiz, Foundries
2020-09-23T11:18:19Z

On 22/09/20, Jens Wiklander wrote:
> On Wed, Sep 16, 2020 at 05:27:32PM +0200, Jorge Ramirez-Ortiz wrote:
> > Allow OP-TEE to specify the number of retries in the adaptor.
> >
> > Signed-off-by: Jorge Ramirez-Ortiz <jorge@foundries.io>
> > ---
> > drivers/tee/optee/rpc.c | 7 +++++++
> > 1 file changed, 7 insertions(+)
> >
> > diff --git a/drivers/tee/optee/rpc.c b/drivers/tee/optee/rpc.c
> > index 1e3614e4798f..2d46a9ecb1de 100644
> > --- a/drivers/tee/optee/rpc.c
> > +++ b/drivers/tee/optee/rpc.c
> > @@ -58,6 +58,7 @@ static void handle_rpc_func_cmd_i2c_transfer(struct tee_context *ctx,
> > struct tee_param *params;
> > size_t i;
> > int ret = -EOPNOTSUPP;
> > + int retries = 0;
> > u8 attr[] = {
> > TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INPUT,
> > TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INPUT,
> > @@ -102,12 +103,17 @@ static void handle_rpc_func_cmd_i2c_transfer(struct tee_context *ctx,
> > client.addr = params[0].u.value.c;
> > snprintf(client.name, I2C_NAME_SIZE, "i2c%d", client.adapter->nr);
> >
> > + /* cache the current value */
> > + retries = client.adapter->retries;
> > +
> > switch (params[0].u.value.a) {
> > case OPTEE_MSG_RPC_CMD_I2C_TRANSFER_RD:
> > + client.adapter->retries = params[1].u.value.b;
> Do we need to take any locks befor this?

no I dont think so: there is no need for bus locks when requesting a
transfer via i2c_master_recv/send; the lock for the bus segment gets
taken later on, when the actual transfer hppens ( __i2c_transfer())

the functionality implemented in this function pretty much mimicks
what is done in the normal world via /dev/i2c-X
(drivers/i2c/i2c_dev.c)

- i2cdev_read --> i2c_master_send
- i2cdev->write -->i2c_master_recv

and now the retry count setup on the adaptor with this commit.

- i2cdev_ioctl I2C_RETRIES

>
> Cheers,
> Jens
>
> > ret = i2c_master_recv(&client, params[2].u.memref.shm->kaddr,
> > params[2].u.memref.size);
> > break;
> > case OPTEE_MSG_RPC_CMD_I2C_TRANSFER_WR:
> > + client.adapter->retries = params[1].u.value.b;
> > ret = i2c_master_send(&client, params[2].u.memref.shm->kaddr,
> > params[2].u.memref.size);
> > break;
> > @@ -126,6 +132,7 @@ static void handle_rpc_func_cmd_i2c_transfer(struct tee_context *ctx,
> > arg->ret = TEEC_SUCCESS;
> > }
> >
> > + client.adapter->retries = retries;
> > i2c_put_adapter(client.adapter);
> > kfree(params);
> > return;
> > --
> > 2.17.1
> >