Re: [PATCH 1/3] Blackfin ethernet driver: on chip ethernet MAC controller driver

On Sun, 2007-07-15 at 09:04 -0400, Dan Williams wrote:

On Sat, 2007-07-14 at 16:38 -0400, Mike Frysinger wrote:

quoted

On 7/14/07, Michael Buesch [off-list ref] wrote:

quoted

On Saturday 14 July 2007 21:49:21 Mike Frysinger wrote:

quoted

On 7/14/07, Michael Buesch [off-list ref] wrote:

quoted

On Saturday 14 July 2007 20:49:53 Bryan Wu wrote:

quoted

+static int __init bf537mac_probe(struct net_device *dev)
+{
+     struct bf537mac_local *lp = netdev_priv(dev);
+     int retval;
+
+     /* Grab the MAC address in the MAC */
+     *(u32 *) (&(dev->dev_addr[0])) = bfin_read_EMAC_ADDRLO();
+     *(u16 *) (&(dev->dev_addr[4])) = (u16) bfin_read_EMAC_ADDRHI();

Endianess broken.

quoted

+struct dma_config_reg {
+     unsigned short b_DMA_EN:1;  /* Bit 0 : DMA Enable */
+     unsigned short b_WNR:1;     /* Bit 1 : DMA Direction */
+     unsigned short b_WDSIZE:2;  /* Bit 2 & 3 : DMA Tranfer Word size */
+     unsigned short b_DMA2D:1;   /* Bit 4 : DMA Mode 2D or 1D */
+     unsigned short b_RESTART:1; /* Bit 5 : Retain the FIFO */
+     unsigned short b_DI_SEL:1;  /* Bit 6 : Data Interrupt Timing Select */
+     unsigned short b_DI_EN:1;   /* Bit 7 : Data Interrupt Enable */
+     unsigned short b_NDSIZE:4;  /* Bit 8 to 11 : Flex descriptor Size */
+     unsigned short b_FLOW:3;    /* Bit 12 to 14 : FLOW */
+};

This is most likely not endianess safe.

do we really need to care about this ?  this is a driver for a MAC
which can only be found on Blackfin processors and Blackfin itself is
only little endian.

Well, this bitfield _might_ be OK (although I don't like bitfields
at all), but the above pointer casting stuff should really use
leXX_to_cpu. It's so easy to use and it is easier to read and
maintain the code afterwards.

i think that's arguable ... i dont see how:
a = foo(b);
is easier to read than:
a = b;
but it is easy to use ... i guess my point was more along the lines of
wasting further time auditing a driver for endianness issues that will
never actually be an issue.

Sometimes by doing this you catch bugs you didn't see before.  It's a
good thing to do generally.  Does sparse with endianness check show
errors?  You may want to fix those.

Dan

Yes, I will add endianess protection as Michael and you mentioned.

Thanks
- Bryan Wu

quoted

-mike
-
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