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SubjectRe: [PATCH v10 06/12] peci: Add a PECI adapter driver for Aspeed AST24xx/AST25xx
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On 1/14/2019 3:37 AM, Joel Stanley wrote:
> On Tue, 8 Jan 2019 at 08:11, Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com> wrote:
>> + ret = of_property_read_u32(priv->dev->of_node, "cmd-timeout-ms",
>> + &priv->cmd_timeout_ms);
>> + if (ret || priv->cmd_timeout_ms > PECI_CMD_TIMEOUT_MS_MAX ||
>> + priv->cmd_timeout_ms == 0) {
>> + if (!ret)
>> + dev_warn(priv->dev,
>> + "Invalid cmd-timeout-ms : %u. Use default : %u\n",
>> + priv->cmd_timeout_ms,
>> + PECI_CMD_TIMEOUT_MS_DEFAULT);
>
> As this property is documented as optional, I'd split out the checks
> so you only warn when the value provided is invalid.
>

Please check the above 'if' statement too. It prints out warning only
when the property is defined in device tree but the value is out of
range.

>> +
>> + regmap_write(priv->regmap, ASPEED_PECI_CTRL,
>> + FIELD_PREP(PECI_CTRL_CLK_DIV_MASK, PECI_CLK_DIV_DEFAULT) |
>> + PECI_CTRL_PECI_CLK_EN);
>> +
>> + /**
>
> Just the one *.
>

Will fix it.

>> + * Timing negotiation period setting.
>> + * The unit of the programmed value is 4 times of PECI clock period.
>> + */
>> + regmap_write(priv->regmap, ASPEED_PECI_TIMING,
>> + FIELD_PREP(PECI_TIMING_MESSAGE_MASK, msg_timing) |
>> + FIELD_PREP(PECI_TIMING_ADDRESS_MASK, addr_timing));
>
>> +static int aspeed_peci_xfer(struct peci_adapter *adapter,
>> + struct peci_xfer_msg *msg)
>> +{
>> + struct aspeed_peci *priv = peci_get_adapdata(adapter);
>> +
>> + return aspeed_peci_xfer_native(priv, msg);
>> +}
>
> It looks like you could do the peci_get_adapdata in
> aspeed_peci_xfer_native and drop the need for this wrapper.
>

Yes, that would be neater. Will remove this wrapper.

>> +
>> +static int aspeed_peci_probe(struct platform_device *pdev)
>> +{
>
>>
>> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> + base = devm_ioremap_resource(&pdev->dev, res);
>> + if (IS_ERR(base)) {
>> + ret = PTR_ERR(base);
>> + goto err_put_adapter_dev;
>> + }
>> +
>> + priv->regmap = devm_regmap_init_mmio(&pdev->dev, base,
>> + &aspeed_peci_regmap_config);
>> + if (IS_ERR(priv->regmap)) {
>> + ret = PTR_ERR(priv->regmap);
>> + goto err_put_adapter_dev;
>> + }
>> +
>> + /**
>> + * We check that the regmap works on this very first access,
>> + * but as this is an MMIO-backed regmap, subsequent regmap
>> + * access is not going to fail and we skip error checks from
>> + * this point.
>
> Why do you use a regmap for this driver? AFAICT it has exclusive
> ownership over the register range it uses, which is sometimes a reason
> to use a regmap over a mmio region.
>
> I'm not sure if you've ever disassembled drivers/base/regmap/regmap.o,
> but if you do you will find that a single mmio read turns into
> hundreds of instructions.
>

No specific reason. regmap makes some overhead as you mentioned but it
also provides some advantages on access simplification, endianness
handling and register dump at run time. I would not insist using of
regmap if you prefer using of raw readl and writel. Do you want replace
regmap with readl and writel in this driver?

Thanks,
Jae

> Cheers,
>
> Joel
>

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