[U-Boot] [v2 2/6] spi: cadence_qspi: remove sram polling from flash read
Marek Vasut
marex at denx.de
Thu Aug 13 22:35:28 CEST 2015
On Thursday, August 13, 2015 at 09:49:49 PM, vikas wrote:
Hi!
> >> On 08/12/2015 07:09 PM, Marek Vasut wrote:
> >>> On Thursday, July 16, 2015 at 04:27:30 AM, Vikas Manocha wrote:
> >>>> There is no need to check for sram fill level. If sram is empty, cpu
> >>>> will go in the wait state till the time data is available from flash.
> >>>
> >>> Consider the following scenario:
> >>> - CPU core reads some memory area, but there are no data available just
> >>> yet
> >>>
> >>> => CPU core goes into wait state
> >>>
> >>> - The data never arrive
> >>>
> >>> Will the CPU be stuck forever ? If we checked the fill level first
> >>> instead, we would never enter such stuck-state.
> >>
> >> This indirect mode of reading/writing would be entered when the
> >> read/write addresses are in the programmed valid range of addresses.
> >>
> >> Even in case of "data never arrive" scenario, a simple timeout seems
> >> better then currently implemented read sram level with timeout.
> >
> > How do you implement a "simple timeout" if the CPU core is stuck and does
> > not execute instructions ? If you mean interrupt, then forget it, U-Boot
> > does not do interrupts ;-)
>
> Oh yes, you are right.
So shall we keep the SRAM piece ?
Best regards,
Marek Vasut
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