| Message ID | 20180808213348.ipppuapqaasrkhxv@linutronix.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] usb: add usb_fill_iso_urb() | expand |
Hi Sebastian, Thank you for the patch. On Thursday, 9 August 2018 00:33:49 EEST Sebastian Andrzej Siewior wrote: > Provide usb_fill_iso_urb() for the initialisation of isochronous URBs. > We already have one of this helpers for control, bulk and interruptible > URB types. This helps to keep the initialisation of the URB members in > one place. > Update the documentation by adding this to the available init functions > and remove the suggestion to use the `_int_' helper which might provide > wrong encoding for the `interval' member. > > This looks like it would cover most users nicely. The sound subsystem > initialises the ->iso_frame_desc[].offset + length member at a different > location and I'm not sure ->interval will work as expected. > > Some users also initialise ->iso_frame_desc[].actual_length but I don't > think that this is required since it is the return value. > > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> > --- > RFC … v2: > - rephrased the interval description as per Alan Stern. > - packets and packet_size can be 0 so the initialisation of > those members will be skipped. Suggested by Alan Stern, came > handy while converting drivers. > - Updated wording as suggested by Laurent Pinchart. > > Documentation/driver-api/usb/URB.rst | 12 +++--- > include/linux/usb.h | 60 ++++++++++++++++++++++++++++ > 2 files changed, 66 insertions(+), 6 deletions(-) > > diff --git a/Documentation/driver-api/usb/URB.rst > b/Documentation/driver-api/usb/URB.rst index 61a54da9fce9..20030b781519 > 100644 > --- a/Documentation/driver-api/usb/URB.rst > +++ b/Documentation/driver-api/usb/URB.rst > @@ -116,11 +116,11 @@ What has to be filled in? > > Depending on the type of transaction, there are some inline functions > defined in ``linux/usb.h`` to simplify the initialization, such as > -:c:func:`usb_fill_control_urb`, :c:func:`usb_fill_bulk_urb` and > -:c:func:`usb_fill_int_urb`. In general, they need the usb device pointer, > -the pipe (usual format from usb.h), the transfer buffer, the desired > transfer -length, the completion handler, and its context. Take a look at > the some -existing drivers to see how they're used. > +:c:func:`usb_fill_control_urb`, :c:func:`usb_fill_bulk_urb`, > +:c:func:`usb_fill_int_urb` and :c:func:`usb_fill_iso_urb`. In general, > they +need the usb device pointer, the pipe (usual format from usb.h), the > transfer +buffer, the desired transfer length, the completion handler, and > its context. +Take a look at the some existing drivers to see how they're > used. > > Flags: > > @@ -243,7 +243,7 @@ Besides the fields present on a bulk transfer, for ISO, > you also also have to set ``urb->interval`` to say how often to make > transfers; it's often one per frame (which is once every microframe for > highspeed devices). The actual interval used will be a power of two that's > no bigger than what -you specify. You can use the > :c:func:`usb_fill_int_urb` macro to fill +you specify. You can use the > :c:func:`usb_fill_iso_urb` macro to fill most ISO transfer fields. > > For ISO transfers you also have to fill a > :c:type:`usb_iso_packet_descriptor` diff --git a/include/linux/usb.h > b/include/linux/usb.h > index 4cdd515a4385..ec1200d53ac5 100644 > --- a/include/linux/usb.h > +++ b/include/linux/usb.h > @@ -1697,6 +1697,66 @@ static inline void usb_fill_int_urb(struct urb *urb, > urb->start_frame = -1; > } > > +/** > + * usb_fill_iso_urb - initializes an isochronous urb > + * @urb: pointer to the urb to initialize. > + * @dev: pointer to the struct usb_device for this urb. > + * @pipe: the endpoint pipe > + * @transfer_buffer: pointer to the transfer buffer > + * @buffer_length: length of the transfer buffer > + * @complete_fn: pointer to the usb_complete_t function > + * @context: what to set the urb context to. > + * @interval: what to set the urb interval to, encoded like > + * the endpoint descriptor's bInterval value. > + * @packets: number of ISO packets. > + * @packet_size: size of each ISO packet. > + * > + * Initializes an isochronous urb with the proper information needed to > submit > + * it to a device. > + * > + * Full-speed devices express polling intervals in frames (1 per ms); > + * high-speed and SuperSpeed devices express polling intervals in > + * microframes (8 per ms). > + * > + * The arguments @packets is to initialize number_of_packets member of > struct > + * usb. If @packets and @packet_size is non zero then the iso_frame_desc > array > + * will be initialized and each packet will have the same size. > + */ > +static inline void usb_fill_iso_urb(struct urb *urb, > + struct usb_device *dev, > + unsigned int pipe, > + void *transfer_buffer, > + int buffer_length, > + usb_complete_t complete_fn, > + void *context, > + int interval, > + unsigned int packets, > + unsigned int packet_size) > +{ > + unsigned int i; > + > + urb->dev = dev; > + urb->pipe = pipe; > + urb->transfer_buffer = transfer_buffer; > + urb->transfer_buffer_length = buffer_length; > + urb->complete = complete_fn; > + urb->context = context; > + > + interval = clamp(interval, 1, 16); > + urb->interval = 1 << (interval - 1); > + urb->start_frame = -1; > + > + if (packets) > + urb->number_of_packets = packets; Do some drivers initialize number_of_packets before calling usb_fill_iso_urb() (or rather usb_fill_int_urb() in the existing code) ? If not, you could assign the field unconditionally, it would just be overwritten by drivers later. > + if (packet_size) { > + for (i = 0; i < packets; i++) { > + urb->iso_frame_desc[i].offset = packet_size * i; > + urb->iso_frame_desc[i].length = packet_size; > + } > + } Same question here. Additionally, do you see use cases for calling this with packets > 0 && packet_size == 0 ? If not the for loop wouldn't iterate at all, so the outer check wouldn't be needed. With or without changes to the above, depending on the use cases, Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> > +} > + > extern void usb_init_urb(struct urb *urb); > extern struct urb *usb_alloc_urb(int iso_packets, gfp_t mem_flags); > extern void usb_free_urb(struct urb *urb);
On Wed, 8 Aug 2018, Sebastian Andrzej Siewior wrote: > Provide usb_fill_iso_urb() for the initialisation of isochronous URBs. > We already have one of this helpers for control, bulk and interruptible > URB types. This helps to keep the initialisation of the URB members in > one place. > Update the documentation by adding this to the available init functions > and remove the suggestion to use the `_int_' helper which might provide > wrong encoding for the `interval' member. > > This looks like it would cover most users nicely. The sound subsystem > initialises the ->iso_frame_desc[].offset + length member at a different > location and I'm not sure ->interval will work as expected. > > Some users also initialise ->iso_frame_desc[].actual_length but I don't > think that this is required since it is the return value. > > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> > --- Very good. Just some minor grammatical points below. > RFC … v2: > - rephrased the interval description as per Alan Stern. > - packets and packet_size can be 0 so the initialisation of > those members will be skipped. Suggested by Alan Stern, came > handy while converting drivers. > - Updated wording as suggested by Laurent Pinchart. > > Documentation/driver-api/usb/URB.rst | 12 +++--- > include/linux/usb.h | 60 ++++++++++++++++++++++++++++ > 2 files changed, 66 insertions(+), 6 deletions(-) > > diff --git a/Documentation/driver-api/usb/URB.rst b/Documentation/driver-api/usb/URB.rst > index 61a54da9fce9..20030b781519 100644 > --- a/Documentation/driver-api/usb/URB.rst > +++ b/Documentation/driver-api/usb/URB.rst > @@ -116,11 +116,11 @@ What has to be filled in? > > Depending on the type of transaction, there are some inline functions > defined in ``linux/usb.h`` to simplify the initialization, such as > -:c:func:`usb_fill_control_urb`, :c:func:`usb_fill_bulk_urb` and > -:c:func:`usb_fill_int_urb`. In general, they need the usb device pointer, > -the pipe (usual format from usb.h), the transfer buffer, the desired transfer > -length, the completion handler, and its context. Take a look at the some > -existing drivers to see how they're used. > +:c:func:`usb_fill_control_urb`, :c:func:`usb_fill_bulk_urb`, > +:c:func:`usb_fill_int_urb` and :c:func:`usb_fill_iso_urb`. In general, they > +need the usb device pointer, the pipe (usual format from usb.h), the transfer > +buffer, the desired transfer length, the completion handler, and its context. > +Take a look at the some existing drivers to see how they're used. s/the //. This mistake was present in the original text, but you might as well fix it now. > > Flags: > > @@ -243,7 +243,7 @@ Besides the fields present on a bulk transfer, for ISO, you also > also have to set ``urb->interval`` to say how often to make transfers; it's > often one per frame (which is once every microframe for highspeed devices). > The actual interval used will be a power of two that's no bigger than what > -you specify. You can use the :c:func:`usb_fill_int_urb` macro to fill > +you specify. You can use the :c:func:`usb_fill_iso_urb` macro to fill > most ISO transfer fields. > > For ISO transfers you also have to fill a :c:type:`usb_iso_packet_descriptor` > diff --git a/include/linux/usb.h b/include/linux/usb.h > index 4cdd515a4385..ec1200d53ac5 100644 > --- a/include/linux/usb.h > +++ b/include/linux/usb.h > @@ -1697,6 +1697,66 @@ static inline void usb_fill_int_urb(struct urb *urb, > urb->start_frame = -1; > } > > +/** > + * usb_fill_iso_urb - initializes an isochronous urb > + * @urb: pointer to the urb to initialize. > + * @dev: pointer to the struct usb_device for this urb. > + * @pipe: the endpoint pipe > + * @transfer_buffer: pointer to the transfer buffer > + * @buffer_length: length of the transfer buffer > + * @complete_fn: pointer to the usb_complete_t function > + * @context: what to set the urb context to. > + * @interval: what to set the urb interval to, encoded like > + * the endpoint descriptor's bInterval value. > + * @packets: number of ISO packets. > + * @packet_size: size of each ISO packet. > + * > + * Initializes an isochronous urb with the proper information needed to submit > + * it to a device. > + * > + * Full-speed devices express polling intervals in frames (1 per ms); > + * high-speed and SuperSpeed devices express polling intervals in > + * microframes (8 per ms). > + * > + * The arguments @packets is to initialize number_of_packets member of struct Insert "the" between "initialize" and "number_of_packets". > + * usb. If @packets and @packet_size is non zero then the iso_frame_desc array s/usb/urb/ s/is/are/ > + * will be initialized and each packet will have the same size. Maybe add: "If @packets is zero then these members are not altered." > + */ > +static inline void usb_fill_iso_urb(struct urb *urb, > + struct usb_device *dev, > + unsigned int pipe, > + void *transfer_buffer, > + int buffer_length, > + usb_complete_t complete_fn, > + void *context, > + int interval, > + unsigned int packets, > + unsigned int packet_size) > +{ > + unsigned int i; > + > + urb->dev = dev; > + urb->pipe = pipe; > + urb->transfer_buffer = transfer_buffer; > + urb->transfer_buffer_length = buffer_length; > + urb->complete = complete_fn; > + urb->context = context; > + > + interval = clamp(interval, 1, 16); > + urb->interval = 1 << (interval - 1); > + urb->start_frame = -1; > + > + if (packets) > + urb->number_of_packets = packets; > + > + if (packet_size) { > + for (i = 0; i < packets; i++) { > + urb->iso_frame_desc[i].offset = packet_size * i; > + urb->iso_frame_desc[i].length = packet_size; > + } > + } > +} > + > extern void usb_init_urb(struct urb *urb); > extern struct urb *usb_alloc_urb(int iso_packets, gfp_t mem_flags); > extern void usb_free_urb(struct urb *urb); Alan Stern
diff --git a/Documentation/driver-api/usb/URB.rst b/Documentation/driver-api/usb/URB.rst index 61a54da9fce9..20030b781519 100644 --- a/Documentation/driver-api/usb/URB.rst +++ b/Documentation/driver-api/usb/URB.rst @@ -116,11 +116,11 @@ What has to be filled in? Depending on the type of transaction, there are some inline functions defined in ``linux/usb.h`` to simplify the initialization, such as -:c:func:`usb_fill_control_urb`, :c:func:`usb_fill_bulk_urb` and -:c:func:`usb_fill_int_urb`. In general, they need the usb device pointer, -the pipe (usual format from usb.h), the transfer buffer, the desired transfer -length, the completion handler, and its context. Take a look at the some -existing drivers to see how they're used. +:c:func:`usb_fill_control_urb`, :c:func:`usb_fill_bulk_urb`, +:c:func:`usb_fill_int_urb` and :c:func:`usb_fill_iso_urb`. In general, they +need the usb device pointer, the pipe (usual format from usb.h), the transfer +buffer, the desired transfer length, the completion handler, and its context. +Take a look at the some existing drivers to see how they're used. Flags: @@ -243,7 +243,7 @@ Besides the fields present on a bulk transfer, for ISO, you also also have to set ``urb->interval`` to say how often to make transfers; it's often one per frame (which is once every microframe for highspeed devices). The actual interval used will be a power of two that's no bigger than what -you specify. You can use the :c:func:`usb_fill_int_urb` macro to fill +you specify. You can use the :c:func:`usb_fill_iso_urb` macro to fill most ISO transfer fields. For ISO transfers you also have to fill a :c:type:`usb_iso_packet_descriptor` diff --git a/include/linux/usb.h b/include/linux/usb.h index 4cdd515a4385..ec1200d53ac5 100644 --- a/include/linux/usb.h +++ b/include/linux/usb.h @@ -1697,6 +1697,66 @@ static inline void usb_fill_int_urb(struct urb *urb, urb->start_frame = -1; } +/** + * usb_fill_iso_urb - initializes an isochronous urb + * @urb: pointer to the urb to initialize. + * @dev: pointer to the struct usb_device for this urb. + * @pipe: the endpoint pipe + * @transfer_buffer: pointer to the transfer buffer + * @buffer_length: length of the transfer buffer + * @complete_fn: pointer to the usb_complete_t function + * @context: what to set the urb context to. + * @interval: what to set the urb interval to, encoded like + * the endpoint descriptor's bInterval value. + * @packets: number of ISO packets. + * @packet_size: size of each ISO packet. + * + * Initializes an isochronous urb with the proper information needed to submit + * it to a device. + * + * Full-speed devices express polling intervals in frames (1 per ms); + * high-speed and SuperSpeed devices express polling intervals in + * microframes (8 per ms). + * + * The arguments @packets is to initialize number_of_packets member of struct + * usb. If @packets and @packet_size is non zero then the iso_frame_desc array + * will be initialized and each packet will have the same size. + */ +static inline void usb_fill_iso_urb(struct urb *urb, + struct usb_device *dev, + unsigned int pipe, + void *transfer_buffer, + int buffer_length, + usb_complete_t complete_fn, + void *context, + int interval, + unsigned int packets, + unsigned int packet_size) +{ + unsigned int i; + + urb->dev = dev; + urb->pipe = pipe; + urb->transfer_buffer = transfer_buffer; + urb->transfer_buffer_length = buffer_length; + urb->complete = complete_fn; + urb->context = context; + + interval = clamp(interval, 1, 16); + urb->interval = 1 << (interval - 1); + urb->start_frame = -1; + + if (packets) + urb->number_of_packets = packets; + + if (packet_size) { + for (i = 0; i < packets; i++) { + urb->iso_frame_desc[i].offset = packet_size * i; + urb->iso_frame_desc[i].length = packet_size; + } + } +} + extern void usb_init_urb(struct urb *urb); extern struct urb *usb_alloc_urb(int iso_packets, gfp_t mem_flags); extern void usb_free_urb(struct urb *urb);
Provide usb_fill_iso_urb() for the initialisation of isochronous URBs. We already have one of this helpers for control, bulk and interruptible URB types. This helps to keep the initialisation of the URB members in one place. Update the documentation by adding this to the available init functions and remove the suggestion to use the `_int_' helper which might provide wrong encoding for the `interval' member. This looks like it would cover most users nicely. The sound subsystem initialises the ->iso_frame_desc[].offset + length member at a different location and I'm not sure ->interval will work as expected. Some users also initialise ->iso_frame_desc[].actual_length but I don't think that this is required since it is the return value. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- RFC … v2: - rephrased the interval description as per Alan Stern. - packets and packet_size can be 0 so the initialisation of those members will be skipped. Suggested by Alan Stern, came handy while converting drivers. - Updated wording as suggested by Laurent Pinchart. Documentation/driver-api/usb/URB.rst | 12 +++--- include/linux/usb.h | 60 ++++++++++++++++++++++++++++ 2 files changed, 66 insertions(+), 6 deletions(-)