Jean-Christophe PLAGNIOL-VILLARD wrote:
>> ---
>> common/cmd_ide.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>> include/ata.h | 4 +++-
>> 2 files changed, 55 insertions(+), 1 deletions(-)
>>
>> diff --git a/common/cmd_ide.c b/common/cmd_ide.c
>> index b4d9719..0e435a7 100644
>> --- a/common/cmd_ide.c
>> +++ b/common/cmd_ide.c
>> @@ -167,6 +167,10 @@ static void input_data(int dev, ulong *sect_buf, int
>> words);
>> static void output_data(int dev, ulong *sect_buf, int words);
>> static void ident_cpy (unsigned char *dest, unsigned char *src, unsigned
>> int len);
>>
>> +#ifdef CONFIG_TUNE_PIO
>> +int inline ide_set_piomode(int pio_mode);
>> +#endif
>> +
>> #ifndef CFG_ATA_PORT_ADDR
>> #define CFG_ATA_PORT_ADDR(port) (port)
>> #endif
>> @@ -838,6 +842,16 @@ __ide_inb(int dev, int port)
>> unsigned char inline ide_inb(int dev, int port)
>> __attribute__((weak, alias("__ide_inb")));
>>
> why not do this?
>
> int inline ide_set_piomode(int pio_mode) __attribute__((weak));
>> #ifdef __PPC__
>> # ifdef CONFIG_AMIGAONEG3SE
>> static void
>> @@ -1054,6 +1068,10 @@ static void ide_ident (block_dev_desc_t *dev_desc)
>> int do_retry = 0;
>> #endif
>>
>> +#ifdef CONFIG_TUNE_PIO
>> + int pio_mode;
>> +#endif
>> +
>> #if 0
>> int mode, cycle_time;
>> #endif
>> @@ -1169,6 +1187,40 @@ static void ide_ident (block_dev_desc_t *dev_desc)
>> else
>> dev_desc->removable = 0;
>>
>> +#ifdef CONFIG_TUNE_PIO
>> + /* Mode 0 - 2 only, are directly determined by word 51. */
>> + pio_mode = iop->tPIO;
>> + if(pio_mode > 2) {
>> + printf("WARNING: Invalid PIO (word 51 = %d).\n", pio_mode);
>> + pio_mode = 0; /* Force it to dead slow, and hope for the
>> best... */
>> + }
>> +
>> + /* Any CompactFlash Storage Card that supports PIO mode 3 or above
>> + * shall set bit 1 of word 53 to one and support the fields contained
>> + * in words 64 through 70.
>> + */
>> + if(iop->field_valid & 0x02) {
>> + /* Mode 3 and above are possible. Check in order from slow
>> + * to fast, so we wind up with the highest mode allowed.
>> + */
>> + if(iop->eide_pio_modes & 0x01) {
>> + pio_mode = 3;
>> + }
>> + if(iop->eide_pio_modes & 0x02) {
>> + pio_mode = 4;
>> + }
>> + if((iop->cf_advanced_caps & 0x07) == 0x01) {
>> + pio_mode = 5;
>> + }
>> + if((iop->cf_advanced_caps & 0x07) == 0x02) {
>> + pio_mode = 6;
>> + }
>> + }
>> +
>> + /* System-specific, depends on bus speeds, etc. */
>
> if(ide_set_piomode)
> ide_set_piomode(pio_mode);
>
> if no ide_set_piomode implementation is present gcc will drop it at
> compile time IIRC.
>
> Best Regards,
> J.
>
At least on the x86, this generates an explicit test, even with -O2. The
generated code looks something like this:
80483cd: b8 00 00 00 00 mov $0x0,%eax
80483d2: 85 c0 test %eax,%eax
80483d4: 74 0c je 80483e2 <main+0x32>
80483d6: c7 04 24 0a 00 00 00 movl $0xa,(%esp)
80483dd: e8 1e 7c fb f7 call 0 <_init-0x8048250>
Is there some explicit optimization flag that causes gcc to drop it at compile
time?
I basically was following the style of the existing code regarding weak
linkage. See for example the ide_outb() implementation. Also, I don't think
your approach eliminates any ifdefs, because we still would not want to perform
the pio_mode calculation unless we intended to use the result.
Steve
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