[U-Boot] [PATCH] driver/ddr: Fix DDR4 driver for ARM

[York Sun]

Noted. Maybe we can pull in part of barrier.h into io.h. It is easier but I am
not sure if it is the cleanest way to go.

York

On 06/19/2014 11:01 AM, Jon Loeliger wrote:
> That might be a fine starting point.  But I might point out
> that U-Boot has some notions down this line already too.
> For example, do a 'git grep wmb' in the U-Boot repo.
> Also ponder arch/arm/include/asm/io.h too.
> 
> HTH,
> jdl
> 
> On Thu, Jun 19, 2014 at 12:47 PM, York Sun <yorksun at freescale.com> wrote:
>> On 06/18/2014 07:57 AM, Jon Loeliger wrote:
>>> On Tue, Jun 17, 2014 at 5:07 PM, York Sun <yorksun at freescale.com> wrote:
>>>> Previously the driver was only tested on Power SoCs. Minor fix is needed
>>>> for ARM SoCs.
>>>>
>>>> Signed-off-by: York Sun <yorksun at freescale.com>
>>>
>>>
>>> Hi York!
>>>
>>>
>>>> --- a/drivers/ddr/fsl/fsl_ddr_gen4.c
>>>> +++ b/drivers/ddr/fsl/fsl_ddr_gen4.c
>>>
>>>> @@ -183,12 +184,20 @@ step2:
>>>>          * we choose the max, that is 500 us for all of case.
>>>>          */
>>>>         udelay(500);
>>>> +#ifdef CONFIG_PPC
>>>>         asm volatile("sync;isync");
>>>> +#else
>>>> +       asm volatile("dsb sy;isb");
>>>> +#endif
>>>>
>>>>         /* Let the controller go */
>>>>         temp_sdram_cfg = ddr_in32(&ddr->sdram_cfg) & ~SDRAM_CFG_BI;
>>>>         ddr_out32(&ddr->sdram_cfg, temp_sdram_cfg | SDRAM_CFG_MEM_EN);
>>>> +#ifdef CONFIG_PPC
>>>>         asm volatile("sync;isync");
>>>> +#else
>>>> +       asm volatile("dsb sy;isb");
>>>> +#endif
>>>>
>>>>         total_gb_size_per_controller = 0;
>>>>         for (i = 0; i < CONFIG_CHIP_SELECTS_PER_CTRL; i++) {
>>>
>>> This is a great example where we should try to introduce better abstractions
>>> in much the same way that Linux has.  Specifically, we (U-Boot) collective
>>> might work toward some common lower-level abstractions such as a
>>> memory_barrier() (and variants), and let those generic names get mapped
>>> into architecture-specific implementations via a linked binding.  Then this
>>> code would not need to change, nor would #ifdefs be needed.
>>>
>>
>> Jon,
>>
>> Are you suggesting to pick arch/<arch>/include/asm/barrier.h from Linux, or part
>> of it?
>>
>> York
>>