* Nicolas Pitre <nico@xxxxxxxxxxx> [101220 13:44]: > On Mon, 20 Dec 2010, Stephen Boyd wrote: > > > The inline assembly differences for v6 vs. v7 in the hvc_dcc > > driver are purely optimizations. On a v7 processor, an mrc with > > the pc sets the condition codes to the 28-31 bits of the register > > being read. It just so happens that the TX/RX full bits the DCC > > driver is testing for are high enough in the register to be put > > into the condition codes. On a v6 processor, this "feature" isn't > > implemented and thus we have to do the usual read, mask, test > > operations to check for TX/RX full. > > > > Since we already test the RX/TX full bits before calling > > __dcc_getchar() and __dcc_putchar() we don't actually need to do > > anything special for v7 over v6. The only difference is in > > hvc_dcc_get_chars(). We would test RX full, poll RX full, and > > then read a character from the buffer, whereas now we will test > > RX full, read a character from the buffer, and then test RX full > > again for the second iteration of the loop. It doesn't seem > > possible for the buffer to go from full to empty between testing > > the RX full and reading a character. Therefore, replace the v7 > > versions with the v6 versions and everything works the same. > > > > Cc: Tony Lindgren <tony@xxxxxxxxxxx> > > Cc: Arnd Bergmann <arnd@xxxxxxxx> > > Cc: Nicolas Pitre <nicolas.pitre@xxxxxxxxxx> > > Cc: Daniel Walker <dwalker@xxxxxxxxxxxxxx> > > Signed-off-by: Stephen Boyd <sboyd@xxxxxxxxxxxxxx> > > Acked-by: Nicolas Pitre <nicolas.pitre@xxxxxxxxxx> Acked-by: Tony Lindgren <tony@xxxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
