On 01/17/2014 12:20 PM, Michal Nazarewicz wrote:
> On Fri, Jan 17 2014, Robert Baldyga wrote:
>> This patch adds poll function for file representing ep0.
>>
>> Ability of read from or write to ep0 file is related with actual state of
>> ffs:
>> - When desctiptors or strings are not written yet, POLLOUT flag is set.
>> - If there is any event to read, POLLIN flag is set.
>> - If setup request was read, POLLIN and POLLOUT flag is set, to allow
>> send response (by performing I/O operation consistent with setup request
>> direction) or set stall (by performing I/O operation opposite setup
>> request direction).
>>
>> Signed-off-by: Robert Baldyga <r.bald...@samsung.com>
>> ---
>> drivers/usb/gadget/f_fs.c | 42 ++++++++++++++++++++++++++++++++++++++++++
>> 1 file changed, 42 insertions(+)
>>
>> diff --git a/drivers/usb/gadget/f_fs.c b/drivers/usb/gadget/f_fs.c
>> @@ -558,6 +560,45 @@ static long ffs_ep0_ioctl(struct file *file, unsigned
>> code, unsigned long value)
>> return ret;
>> }
>>
>> +static unsigned int ffs_ep0_poll(struct file *file, poll_table *wait)
>> +{
>> + struct ffs_data *ffs = file->private_data;
>> + unsigned int mask = POLLWRNORM;
>> + int ret;
>> +
>> + ret = ffs_mutex_lock(&ffs->mutex, file->f_flags & O_NONBLOCK);
>> + if (unlikely(ret < 0))
>> + return mask;
>> +
>> + switch (ffs->state) {
>> + case FFS_READ_DESCRIPTORS:
>> + case FFS_READ_STRINGS:
>> + mask |= POLLOUT;
>> + break;
>> +
>> + case FFS_ACTIVE:
>> + switch (FFS_SETUP_STATE(ffs)) {
>> + case FFS_NO_SETUP:
>> + if (ffs->ev.count)
>> + mask |= POLLIN;
>> + break;
>> +
>> + case FFS_SETUP_PENDING:
>> + mask |= (POLLIN | POLLOUT);
>> + break;
>> +
>> + case FFS_SETUP_CANCELED:
>
> The FFS_SETUP_CANCELED and FFS_SETUP_PENDING are the same case. ep0
> never recovers from FFS_SETUP_CANCELED on its own, it waits for user
> space to attempt to read or write something. So unless I'm missing
> something the two cases should be merged together and in both POLLIN and
> POLLOUT needs to be set.
>
Hmm, it seems like it doesn't work this way. In both read and write
functions in ep0 file operations, there is check at the beginning:
if (FFS_SETUP_STATE(ffs) == FFS_SETUP_CANCELED)
return -EIDRM;
So read/write does nothing when FFS_SETUP_CANCELED state is set.
>> + break;
>> + }
>> + case FFS_CLOSING:
>> + break;
>> + }
>> +
>> + mutex_unlock(&ffs->mutex);
>> +
>> + return mask;
>> +}
>> +
>> static const struct file_operations ffs_ep0_operations = {
>> .llseek = no_llseek,
>>
>
>
>
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
