[PATCH] drm/repaper: combine allocs in repaper_spi_transfer()

[trix]

From: Tom Rix <t...@redhat.com>

repaper_spi_transfer() allocates a single byte
for the spi header and then another buffer for
the payload.  Combine the allocs into a single
buffer with offsets.  To simplify the offsets
put the header after the payload.

Signed-off-by: Tom Rix <t...@redhat.com>
---
 drivers/gpu/drm/tiny/repaper.c | 40 ++++++++++------------------------
 1 file changed, 12 insertions(+), 28 deletions(-)

diff --git a/drivers/gpu/drm/tiny/repaper.c b/drivers/gpu/drm/tiny/repaper.c
index 37b6bb90e46e1..22a6732f35a01 100644
--- a/drivers/gpu/drm/tiny/repaper.c
+++ b/drivers/gpu/drm/tiny/repaper.c
@@ -100,50 +100,34 @@ static inline struct repaper_epd *drm_to_epd(struct 
drm_device *drm)
 static int repaper_spi_transfer(struct spi_device *spi, u8 header,
                                const void *tx, void *rx, size_t len)
 {
-       void *txbuf = NULL, *rxbuf = NULL;
        struct spi_transfer tr[2] = {};
-       u8 *headerbuf;
+       u8 *buf;
        int ret;
 
-       headerbuf = kmalloc(1, GFP_KERNEL);
-       if (!headerbuf)
+       buf = kmalloc(1 + len, GFP_KERNEL);
+       if (!buf)
                return -ENOMEM;
 
-       headerbuf[0] = header;
-       tr[0].tx_buf = headerbuf;
+       buf[len] = header;
+       tr[0].tx_buf = &buf[len];
        tr[0].len = 1;
 
-       /* Stack allocated tx? */
-       if (tx && len <= 32) {
-               txbuf = kmemdup(tx, len, GFP_KERNEL);
-               if (!txbuf) {
-                       ret = -ENOMEM;
-                       goto out_free;
-               }
+       if (tx) {
+               memcpy(buf, tx, len);
+               tr[1].tx_buf = buf;
        }
 
-       if (rx) {
-               rxbuf = kmalloc(len, GFP_KERNEL);
-               if (!rxbuf) {
-                       ret = -ENOMEM;
-                       goto out_free;
-               }
-       }
+       if (rx)
+               tr[1].rx_buf = buf;
 
-       tr[1].tx_buf = txbuf ? txbuf : tx;
-       tr[1].rx_buf = rxbuf;
        tr[1].len = len;
 
        ndelay(80);
        ret = spi_sync_transfer(spi, tr, 2);
        if (rx && !ret)
-               memcpy(rx, rxbuf, len);
-
-out_free:
-       kfree(headerbuf);
-       kfree(txbuf);
-       kfree(rxbuf);
+               memcpy(rx, buf, len);
 
+       kfree(buf);
        return ret;
 }
 
-- 
2.26.3