[RFC PATCH] usb: gadget: f_tcm: Added DMA32 flag while allocation of command buffer

[Jayshri Pawar <jpawar@xxxxxxxxxxx>]

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.

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