zhao, forrest wrote:
Hi, Jeff
When reading ahci_port_start(), I found the
following code segments:
.......
if (hpriv->cap & HOST_CAP_64)
writel((pp->cmd_slot_dma >> 16) >> 16, port_mmio +
PORT_LST_ADDR_HI);
writel(pp->cmd_slot_dma & 0xffffffff, port_mmio +
PORT_LST_ADDR);
readl(port_mmio + PORT_LST_ADDR); /* flush */
......
I can't figure out why you use ">>16>>16" instead of
">>32" for right-shift 32 bits.
dma_addr_t is 32bits on some architectures and C hates when you do 32
bit shift to 32bit variable.
$ cat test.c
#include <sys/types.h>
int main(void)
{
u_int32_t t = 1234;
t = t >> 32;
return 0;
}
$ gcc test.c
test.c: In function 'main':
test.c:6: warning: right shift count >= width of type
--
tejun
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