Re: [RFC PATCH] usb: gadget: f_tcm: Added DMA32 flag while allocation of command buffer
From: Roger Quadros
Date: Thu Nov 14 2019 - 04:48:18 EST
Jayshri,
On 14/11/2019 04:50, Peter Chen wrote:
On 19-11-13 10:24:32, Jayshri Pawar wrote:
There is a problem when function driver allocate memory for buffer
used by DMA from outside dma_mask space.
It appears during testing f_tcm driver with cdns3 controller.
In the result cdns3 driver was not able to map virtual buffer to DMA.
This fix should be improved depending on dma_mask associated with device.
Adding GFP_DMA32 flag while allocationg command data buffer only for 32
bit controllers.
Hi Jayshri,
This issue should be fixed by setting DMA_MASK correctly for controller,
you can't limit user's memory region. At usb_ep_queue, the UDC driver
will call DMA MAP API, for Cadence, it is usb_gadget_map_request_by_dev.
For the system without SMMU (IO-MMU), it will use swiotlb to make sure
the data buffer used for DMA transfer is within DMA mask for controller,
There is a reserved low memory region for debounce buffer in swiotlb
use case.
/**
* struct usb_request - describes one i/o request
* @buf: Buffer used for data. Always provide this; some controllers
* only use PIO, or don't use DMA for some endpoints.
* @dma: DMA address corresponding to 'buf'. If you don't set this
* field, and the usb controller needs one, it is responsible
* for mapping and unmapping the buffer.
<snip>
*/
So if dma is not set in the usb_request then controller driver is
responsible to do a dma_map of the buffer pointed by 'buf' before
it attemps to do DMA. This should take care of DMA mask and swiotlb.
This patch is not correct.
cheers,
-roger
Peter
Signed-off-by: Pawel Laszczak <pawell@xxxxxxxxxxx>
Signed-off-by: Jayshri Pawar <jpawar@xxxxxxxxxxx>
---
drivers/usb/gadget/function/f_tcm.c | 20 ++++++++++++++------
include/linux/usb/gadget.h | 2 ++
2 files changed, 16 insertions(+), 6 deletions(-)
diff --git a/drivers/usb/gadget/function/f_tcm.c b/drivers/usb/gadget/function/f_tcm.c
index 36504931b2d1..a78d5fad3d84 100644
--- a/drivers/usb/gadget/function/f_tcm.c
+++ b/drivers/usb/gadget/function/f_tcm.c
@@ -213,7 +213,8 @@ static int bot_send_read_response(struct usbg_cmd *cmd)
}
if (!gadget->sg_supported) {
- cmd->data_buf = kmalloc(se_cmd->data_length, GFP_ATOMIC);
+ cmd->data_buf = kmalloc(se_cmd->data_length, GFP_ATOMIC |
+ gadget->dma_flag);
if (!cmd->data_buf)
return -ENOMEM;
@@ -257,7 +258,8 @@ static int bot_send_write_request(struct usbg_cmd *cmd)
}
if (!gadget->sg_supported) {
- cmd->data_buf = kmalloc(se_cmd->data_length, GFP_KERNEL);
+ cmd->data_buf = kmalloc(se_cmd->data_length, GFP_KERNEL |
+ gadget->dma_flag);
if (!cmd->data_buf)
return -ENOMEM;
@@ -305,6 +307,7 @@ static void bot_cmd_complete(struct usb_ep *ep, struct usb_request *req)
static int bot_prepare_reqs(struct f_uas *fu)
{
int ret;
+ struct usb_gadget *gadget = fuas_to_gadget(fu);
fu->bot_req_in = usb_ep_alloc_request(fu->ep_in, GFP_KERNEL);
if (!fu->bot_req_in)
@@ -327,7 +330,8 @@ static int bot_prepare_reqs(struct f_uas *fu)
fu->bot_status.req->complete = bot_status_complete;
fu->bot_status.csw.Signature = cpu_to_le32(US_BULK_CS_SIGN);
- fu->cmd.buf = kmalloc(fu->ep_out->maxpacket, GFP_KERNEL);
+ fu->cmd.buf = kmalloc(fu->ep_out->maxpacket, GFP_KERNEL |
+ gadget->dma_flag);
if (!fu->cmd.buf)
goto err_buf;
@@ -515,7 +519,8 @@ static int uasp_prepare_r_request(struct usbg_cmd *cmd)
struct uas_stream *stream = cmd->stream;
if (!gadget->sg_supported) {
- cmd->data_buf = kmalloc(se_cmd->data_length, GFP_ATOMIC);
+ cmd->data_buf = kmalloc(se_cmd->data_length, GFP_ATOMIC |
+ gadget->dma_flag);
if (!cmd->data_buf)
return -ENOMEM;
@@ -763,11 +768,13 @@ static int uasp_alloc_stream_res(struct f_uas *fu, struct uas_stream *stream)
static int uasp_alloc_cmd(struct f_uas *fu)
{
+ struct usb_gadget *gadget = fuas_to_gadget(fu);
fu->cmd.req = usb_ep_alloc_request(fu->ep_cmd, GFP_KERNEL);
if (!fu->cmd.req)
goto err;
- fu->cmd.buf = kmalloc(fu->ep_cmd->maxpacket, GFP_KERNEL);
+ fu->cmd.buf = kmalloc(fu->ep_cmd->maxpacket, GFP_KERNEL |
+ gadget->dma_flag);
if (!fu->cmd.buf)
goto err_buf;
@@ -980,7 +987,8 @@ static int usbg_prepare_w_request(struct usbg_cmd *cmd, struct usb_request *req)
struct usb_gadget *gadget = fuas_to_gadget(fu);
if (!gadget->sg_supported) {
- cmd->data_buf = kmalloc(se_cmd->data_length, GFP_ATOMIC);
+ cmd->data_buf = kmalloc(se_cmd->data_length, GFP_ATOMIC |
+ gadget->dma_flag);
if (!cmd->data_buf)
return -ENOMEM;
diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
index 124462d65eac..d6c9cd222600 100644
--- a/include/linux/usb/gadget.h
+++ b/include/linux/usb/gadget.h
@@ -373,6 +373,7 @@ struct usb_gadget_ops {
* @connected: True if gadget is connected.
* @lpm_capable: If the gadget max_speed is FULL or HIGH, this flag
* indicates that it supports LPM as per the LPM ECN & errata.
+ * @dma_flag: dma zone to be used for buffer allocation.
*
* Gadgets have a mostly-portable "gadget driver" implementing device
* functions, handling all usb configurations and interfaces. Gadget
@@ -427,6 +428,7 @@ struct usb_gadget {
unsigned deactivated:1;
unsigned connected:1;
unsigned lpm_capable:1;
+ unsigned int dma_flag;
};
#define work_to_gadget(w) (container_of((w), struct usb_gadget, work))
--
2.20.1
--
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki