Hi Michael On 18/10/2022 15:04, Michael Grzeschik wrote:
Hi Dan! Hi Dan! On Tue, Oct 18, 2022 at 02:27:13PM +0100, Dan Scally wrote:Hi Dan On 17/10/2022 21:54, Dan Vacura wrote:The scatter gather support doesn't appear to work well with some UDC hw.Add the ability to turn on the feature depending on the controller in use. Signed-off-by: Dan Vacura <w36195@xxxxxxxxxxxx>Nitpick: I would call it use_sg everywhere, but either way:Or even only "scatter_gather". How does that sound?Reviewed-by: Daniel Scally <dan.scally@xxxxxxxxxxxxxxxx> Tested-by: Daniel Scally <dan.scally@xxxxxxxxxxxxxxxx>--- V1 -> V2: - no change, new patch in serie V2 -> V3: - default on, same as baseline Documentation/ABI/testing/configfs-usb-gadget-uvc | 1 + Documentation/usb/gadget-testing.rst | 2 ++ drivers/usb/gadget/function/f_uvc.c | 2 ++ drivers/usb/gadget/function/u_uvc.h | 1 + drivers/usb/gadget/function/uvc_configfs.c | 2 ++ drivers/usb/gadget/function/uvc_queue.c | 4 ++-- 6 files changed, 10 insertions(+), 2 deletions(-)diff --git a/Documentation/ABI/testing/configfs-usb-gadget-uvc b/Documentation/ABI/testing/configfs-usb-gadget-uvcindex 5dfaa3f7f6a4..839a75fc28ee 100644 --- a/Documentation/ABI/testing/configfs-usb-gadget-uvc +++ b/Documentation/ABI/testing/configfs-usb-gadget-uvc @@ -9,6 +9,7 @@ Description: UVC function directory streaming_interval 1..16 function_name string [32] req_int_skip_div unsigned int + sg_supported 0..1 =================== ============================= What: /config/usb-gadget/gadget/functions/uvc.name/controldiff --git a/Documentation/usb/gadget-testing.rst b/Documentation/usb/gadget-testing.rstindex f9b5a09be1f4..8e3072d6a590 100644 --- a/Documentation/usb/gadget-testing.rst +++ b/Documentation/usb/gadget-testing.rst@@ -796,6 +796,8 @@ The uvc function provides these attributes in its function directory:function_name name of the interfacereq_int_skip_div divisor of total requests to aid in calculatinginterrupt frequency, 0 indicates all interrupt + sg_supported allow for scatter gather to be used if the UDC + hw supports it=================== ================================================ There are also "control" and "streaming" subdirectories, each of which contain diff --git a/drivers/usb/gadget/function/f_uvc.c b/drivers/usb/gadget/function/f_uvc.cindex e40ca26b9c55..d08ebe3ffeb2 100644 --- a/drivers/usb/gadget/function/f_uvc.c +++ b/drivers/usb/gadget/function/f_uvc.c@@ -656,6 +656,7 @@ uvc_function_bind(struct usb_configuration *c, struct usb_function *f)(opts->streaming_maxburst + 1)); uvc->config_skip_int_div = opts->req_int_skip_div; + uvc->video.queue.use_sg = opts->sg_supported;Why do you set this here?/* Allocate endpoints. */ ep = usb_ep_autoconfig(cdev->gadget, &uvc_control_ep);@@ -875,6 +876,7 @@ static struct usb_function_instance *uvc_alloc_inst(void)opts->streaming_interval = 1; opts->streaming_maxpacket = 1024; opts->req_int_skip_div = 4; + opts->sg_supported = 1;snprintf(opts->function_name, sizeof(opts->function_name), "UVC Camera");ret = uvcg_attach_configfs(opts);diff --git a/drivers/usb/gadget/function/u_uvc.h b/drivers/usb/gadget/function/u_uvc.hindex 6f73bd5638ed..5ccced629925 100644 --- a/drivers/usb/gadget/function/u_uvc.h +++ b/drivers/usb/gadget/function/u_uvc.h @@ -25,6 +25,7 @@ struct f_uvc_opts { unsigned int streaming_maxpacket; unsigned int streaming_maxburst; unsigned int req_int_skip_div; + unsigned int sg_supported; unsigned int control_interface; unsigned int streaming_interface;diff --git a/drivers/usb/gadget/function/uvc_configfs.c b/drivers/usb/gadget/function/uvc_configfs.cindex 419e926ab57e..3784c0e02d01 100644 --- a/drivers/usb/gadget/function/uvc_configfs.c +++ b/drivers/usb/gadget/function/uvc_configfs.c@@ -2351,6 +2351,7 @@ UVCG_OPTS_ATTR(streaming_interval, streaming_interval, 16);UVCG_OPTS_ATTR(streaming_maxpacket, streaming_maxpacket, 3072); UVCG_OPTS_ATTR(streaming_maxburst, streaming_maxburst, 15); UVCG_OPTS_ATTR(req_int_skip_div, req_int_skip_div, UINT_MAX); +UVCG_OPTS_ATTR(sg_supported, sg_supported, 1); #undef UVCG_OPTS_ATTR @@ -2401,6 +2402,7 @@ static struct configfs_attribute *uvc_attrs[] = { &f_uvc_opts_attr_streaming_maxpacket, &f_uvc_opts_attr_streaming_maxburst, &f_uvc_opts_attr_req_int_skip_div, + &f_uvc_opts_attr_sg_supported, &f_uvc_opts_string_attr_function_name, NULL, };diff --git a/drivers/usb/gadget/function/uvc_queue.c b/drivers/usb/gadget/function/uvc_queue.cindex 02559906a55a..3c7aa5c4bba2 100644 --- a/drivers/usb/gadget/function/uvc_queue.c +++ b/drivers/usb/gadget/function/uvc_queue.c@@ -149,11 +149,11 @@ int uvcg_queue_init(struct uvc_video_queue *queue, struct device *dev, enum v4l2queue->queue.buf_struct_size = sizeof(struct uvc_buffer); queue->queue.ops = &uvc_queue_qops; queue->queue.lock = lock; - if (cdev->gadget->sg_supported) { + if (queue->use_sg && cdev->gadget->sg_supported) { queue->queue.mem_ops = &vb2_dma_sg_memops; - queue->use_sg = 1; } else { queue->queue.mem_ops = &vb2_vmalloc_memops; + queue->use_sg = false;I am unsure, but can you actually not always use vb2_dma_sg_memops.
We have problems with this on the imx8mp EVK, because it doesn't account for dma-range properties in device tree and so will attempt to allocate memory outside the 4GB range that a DWC3 can access. The allocation attempts to fall back on the swiotlb, but that's slow even if it works...and it can fail and return -ENOMEM if the swiotlb is too small.
Probably some future work needs to fix the vb2_dma_sg_memops to take those dma constraints into account, but for now I wouldn't force its use.
With my last patch we always set buf->mem to vb2_plane_vaddr(vb, 0);https://lore.kernel.org/linux-usb/20221017221141.3134818-1-m.grzeschik@xxxxxxxxxxxxxx/T/#uThe condition to decide if encode_isoc_sg or encode_isoc should then remain the last place to switch between sg or not. I would hook the userspace decision in here. You can also directly get to opts->scatter_gather by using struct f_uvc_opts *opts = fi_to_f_uvc_opts(uvc->func.fi); in the function uvcg_video_enable.} queue->queue.timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_COPYThanks, Michael
