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SubjectRe: [PATCH 1/7] mtd: spi-nor: cadence-quadspi: add a delay in write sequence
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On Thursday 10 August 2017 05:35 AM, Rob Herring wrote:
> On Tue, Aug 01, 2017 at 10:24:28AM +0530, Vignesh R wrote:
>> As per 66AK2G02 TRM[1] SPRUHY8F section 11.15.5.3 Indirect Access
>> Controller programming sequence, a delay equal to couple QSPI master
>> clock(~5ns) is required after setting CQSPI_REG_INDIRECTWR_START bit and
>> writing data to the flash. Add a new compatible to handle the couple of
>> cycles of delay required in the indirect write sequence, since this
>> delay is specific to TI 66AK2G SoC.
>>
>> [1]http://www.ti.com/lit/ug/spruhy8f/spruhy8f.pdf
>>
[...]
>> + /*
>> + * As per 66AK2G02 TRM SPRUHY8F section 11.15.5.3 Indirect Access
>> + * Controller programming sequence, couple of cycles of
>> + * QSPI_REF_CLK delay is required for the above bit to
>> + * be internally synchronized by the QSPI module. Provide 5
>> + * cycles of delay.
>> + */
>> + ndelay(cqspi->wr_delay);
>>
>> while (remaining > 0) {
>> write_bytes = remaining > page_size ? page_size : remaining;
>> @@ -1213,6 +1222,9 @@ static int cqspi_probe(struct platform_device *pdev)
>> }
>>
>> cqspi->master_ref_clk_hz = clk_get_rate(cqspi->clk);
>> + if (of_device_is_compatible(dev->of_node, "ti,k2g-qspi"))
>> + cqspi->wr_delay = 5 * DIV_ROUND_UP(NSEC_PER_SEC,
>> + cqspi->master_ref_clk_hz);
>
> Use the data pointer in the of_device_id table and put the delay value
> there.
>

I thought about this, but for a given SoC, delay value might vary
depending on what frequency QSPI master_ref_clk is set to. So hard
coding will not help. How about having a flag (CQSPI_NEEDS_WR_DELAY) in
data pointer and then using that to determine whether or not to
calculate and set delay here?

>>
>> ret = devm_request_irq(dev, irq, cqspi_irq_handler, 0,
>> pdev->name, cqspi);
>> @@ -1285,6 +1297,7 @@ static const struct dev_pm_ops cqspi__dev_pm_ops = {
>>
>> static const struct of_device_id cqspi_dt_ids[] = {
>> {.compatible = "cdns,qspi-nor",},
>> + {.compatible = "ti,k2g-qspi",},
>> { /* end of table */ }
>> };
>>
>> --
>> 2.13.3
>>

--
Regards
Vignesh

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