The buffer used to store firmware is allocated to maximum firmware
size (TI_FIRMWARE_BUF_SIZE) + header size.
This buffer is filled with requested firmware (fw_p->size) and padded
with 0xff bytes. The header is written over the 3 first bytes of the
buffer (overwritting the 3 first bytes of the requested firmware)

Then, ti_do_download function is called to send only the first
fw_p->size bytes from the buffer to the device.
The rest of the buffer is never used.

So it is sufficient to allocate a buffer of fw_p->size bytes to store
only the requested firmware. There is no need to do any padding.

This patch also move firmware buffer manipulation to ti_do_download
function.

Signed-off-by: Mathieu OTHACEHE <m.othac...@gmail.com>
---
 drivers/usb/serial/ti_usb_3410_5052.c | 61 +++++++++++++++++++----------------
 1 file changed, 33 insertions(+), 28 deletions(-)

diff --git a/drivers/usb/serial/ti_usb_3410_5052.c 
b/drivers/usb/serial/ti_usb_3410_5052.c
index 472971b..b46a511 100644
--- a/drivers/usb/serial/ti_usb_3410_5052.c
+++ b/drivers/usb/serial/ti_usb_3410_5052.c
@@ -1639,46 +1639,65 @@ static int ti_write_byte(struct usb_serial_port *port, 
u32 addr,
        return status;
 }
 
-static int ti_do_download(struct usb_device *dev, int pipe,
-                         u8 *buffer, int size)
+static int ti_do_download(struct usb_serial *serial,
+                         const struct firmware *fw_p)
 {
        int pos;
        u8 cs = 0;
        int done;
+       struct usb_device *dev = serial->dev;
        struct ti_firmware_header *header;
        int status = 0;
+       u8 *buffer;
+       int buffer_size;
        int len;
+       unsigned int pipe;
+
+       pipe = usb_sndbulkpipe(dev, serial->port[0]->bulk_out_endpointAddress);
+
+       buffer_size = fw_p->size;
+       buffer = kmalloc(buffer_size, GFP_KERNEL);
+       if (!buffer)
+               return -ENOMEM;
 
-       for (pos = sizeof(struct ti_firmware_header); pos < size; pos++)
+       memcpy(buffer, fw_p->data, fw_p->size);
+
+       for (pos = sizeof(*header); pos < buffer_size; pos++)
                cs = (u8)(cs + buffer[pos]);
 
        header = (struct ti_firmware_header *)buffer;
-       header->wLength = cpu_to_le16(size - sizeof(*header));
+       header->wLength = cpu_to_le16(buffer_size - sizeof(*header));
        header->bCheckSum = cs;
 
        dev_dbg(&dev->dev, "%s - downloading firmware\n", __func__);
-       for (pos = 0; pos < size; pos += done) {
-               len = min(size - pos, TI_DOWNLOAD_MAX_PACKET_SIZE);
+       for (pos = 0; pos < buffer_size; pos += done) {
+               len = min(buffer_size - pos, TI_DOWNLOAD_MAX_PACKET_SIZE);
                status = usb_bulk_msg(dev, pipe, buffer + pos, len, &done,
                                      TI_DOWNLOAD_TIMEOUT);
                if (status)
                        break;
        }
-       return status;
+
+       kfree(buffer);
+
+       if (status) {
+               dev_err(&dev->dev, "failed to download firmware: %d\n", status);
+               return status;
+       }
+
+       dev_dbg(&dev->dev, "%s - download successful\n", __func__);
+
+       return 0;
 }
 
 static int ti_download_firmware(struct usb_serial *serial)
 {
        int status;
-       int buffer_size;
-       u8 *buffer;
        struct usb_device *dev = serial->dev;
        struct ti_device *tdev = usb_get_serial_data(serial);
-       unsigned int pipe;
        const struct firmware *fw_p;
        char buf[32];
 
-       pipe = usb_sndbulkpipe(dev, serial->port[0]->bulk_out_endpointAddress);
 
        if (le16_to_cpu(dev->descriptor.idVendor) == MXU1_VENDOR_ID) {
                snprintf(buf,
@@ -1733,30 +1752,16 @@ check_firmware:
                dev_err(&dev->dev, "%s - firmware not found\n", __func__);
                return -ENOENT;
        }
+
        if (fw_p->size > TI_FIRMWARE_BUF_SIZE) {
                dev_err(&dev->dev, "%s - firmware too large %zu\n", __func__, 
fw_p->size);
                release_firmware(fw_p);
                return -ENOENT;
        }
 
-       buffer_size = TI_FIRMWARE_BUF_SIZE + sizeof(struct ti_firmware_header);
-       buffer = kmalloc(buffer_size, GFP_KERNEL);
-       if (buffer) {
-               memcpy(buffer, fw_p->data, fw_p->size);
-               memset(buffer + fw_p->size, 0xff, buffer_size - fw_p->size);
-               status = ti_do_download(dev, pipe, buffer, fw_p->size);
-               kfree(buffer);
-       } else {
-               status = -ENOMEM;
-       }
-       release_firmware(fw_p);
-       if (status) {
-               dev_err(&dev->dev, "%s - error downloading firmware, %d\n",
-                                                       __func__, status);
-               return status;
-       }
+       ti_do_download(serial, fw_p);
 
-       dev_dbg(&dev->dev, "%s - download successful\n", __func__);
+       release_firmware(fw_p);
 
        return 0;
 }
-- 
2.9.0

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