media: ddbridge: make (ddb)readl in while-loops fail-safe

Reported by smatch:

  drivers/media/pci/ddbridge/ddbridge-core.c:1246 input_tasklet() warn: this loop depends on readl() succeeding
  drivers/media/pci/ddbridge/ddbridge-core.c:1768 flashio() warn: this loop depends on readl() succeeding
  drivers/media/pci/ddbridge/ddbridge-core.c:1788 flashio() warn: this loop depends on readl() succeeding

Fix this by introducing safe_ddbreadl() which will wrap ddbreadl and checks
for all bits set in the return which indicates failure, and return 0 in
that case. Usable as drop-in-replacement in all affected while loops w/o
having to change the logic.
Signed-off-by: Daniel Scheller <d.scheller@gmx.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/pci/ddbridge/ddbridge-core.c

@@ -114,6 +114,19 @@ static int i2c_write_reg(struct i2c_adapter *adap, u8 adr,
 	return i2c_write(adap, adr, msg, 2);
 }
 
+static inline u32 safe_ddbreadl(struct ddb *dev, u32 adr)
+{
+	u32 val = ddbreadl(adr);
+
+	/* (ddb)readl returns (uint)-1 (all bits set) on failure, catch that */
+	if (val == ~0) {
+		printk(KERN_ERR "ddbreadl failure, adr=%08x\n", adr);
+		return 0;
+	}
+
+	return val;
+}
+
 static int ddb_i2c_cmd(struct ddb_i2c *i2c, u32 adr, u32 cmd)
 {
 	struct ddb *dev = i2c->dev;
@@ -1243,7 +1256,7 @@ static void input_tasklet(unsigned long data)
 		if (4&ddbreadl(DMA_BUFFER_CONTROL(input->nr)))
 			printk(KERN_ERR "Overflow input %d\n", input->nr);
 		while (input->cbuf != ((input->stat >> 11) & 0x1f)
-		       || (4&ddbreadl(DMA_BUFFER_CONTROL(input->nr)))) {
+		       || (4 & safe_ddbreadl(dev, DMA_BUFFER_CONTROL(input->nr)))) {
 			dvb_dmx_swfilter_packets(&input->demux,
 						 input->vbuf[input->cbuf],
 						 input->dma_buf_size / 188);
@@ -1765,7 +1778,7 @@ static int flashio(struct ddb *dev, u8 *wbuf, u32 wlen, u8 *rbuf, u32 rlen)
 		wbuf += 4;
 		wlen -= 4;
 		ddbwritel(data, SPI_DATA);
-		while (ddbreadl(SPI_CONTROL) & 0x0004)
+		while (safe_ddbreadl(dev, SPI_CONTROL) & 0x0004)
 			;
 	}
 
@@ -1785,7 +1798,7 @@ static int flashio(struct ddb *dev, u8 *wbuf, u32 wlen, u8 *rbuf, u32 rlen)
 	if (shift)
 		data <<= shift;
 	ddbwritel(data, SPI_DATA);
-	while (ddbreadl(SPI_CONTROL) & 0x0004)
+	while (safe_ddbreadl(dev, SPI_CONTROL) & 0x0004)
 		;
 
 	if (!rlen) {
@@ -1797,7 +1810,7 @@ static int flashio(struct ddb *dev, u8 *wbuf, u32 wlen, u8 *rbuf, u32 rlen)
 
 	while (rlen > 4) {
 		ddbwritel(0xffffffff, SPI_DATA);
-		while (ddbreadl(SPI_CONTROL) & 0x0004)
+		while (safe_ddbreadl(dev, SPI_CONTROL) & 0x0004)
 			;
 		data = ddbreadl(SPI_DATA);
 		*(u32 *) rbuf = swab32(data);
@@ -1806,7 +1819,7 @@ static int flashio(struct ddb *dev, u8 *wbuf, u32 wlen, u8 *rbuf, u32 rlen)
 	}
 	ddbwritel(0x0003 | ((rlen << (8 + 3)) & 0x1F00), SPI_CONTROL);
 	ddbwritel(0xffffffff, SPI_DATA);
-	while (ddbreadl(SPI_CONTROL) & 0x0004)
+	while (safe_ddbreadl(dev, SPI_CONTROL) & 0x0004)
 		;
 
 	data = ddbreadl(SPI_DATA);