Re: [PATCH v3 06/10] mtd: intel-dg: wake card on operations

["Poosa, Karthik" <karthik.poosa@intel.com>]

On 18-12-2024 04:19, Rodrigo Vivi wrote:
> On Tue, Nov 19, 2024 at 04:01:08PM +0200, Alexander Usyskin wrote:
>> Enable runtime PM in mtd driver to notify graphics driver that
>> whole card should be kept awake while nvm operations are
>> performed through this driver.
>>
>> CC: Lucas De Marchi <lucas.demarchi@intel.com>
>> Acked-by: Miquel Raynal <miquel.raynal@bootlin.com>
>> Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
>> ---
>>   drivers/mtd/devices/mtd-intel-dg.c | 70 +++++++++++++++++++++++++-----
>>   1 file changed, 58 insertions(+), 12 deletions(-)
>>
>> diff --git a/drivers/mtd/devices/mtd-intel-dg.c b/drivers/mtd/devices/mtd-intel-dg.c
>> index 230bf444b7fe..9dd23b11ee95 100644
>> --- a/drivers/mtd/devices/mtd-intel-dg.c
>> +++ b/drivers/mtd/devices/mtd-intel-dg.c
>> @@ -15,11 +15,14 @@
>>   #include <linux/module.h>
>>   #include <linux/mtd/mtd.h>
>>   #include <linux/mtd/partitions.h>
>> +#include <linux/pm_runtime.h>
>>   #include <linux/string.h>
>>   #include <linux/slab.h>
>>   #include <linux/sizes.h>
>>   #include <linux/types.h>
>>   
>> +#define INTEL_DG_NVM_RPM_TIMEOUT 500
>> +
>>   struct intel_dg_nvm {
>>   	struct kref refcnt;
>>   	struct mtd_info mtd;
>> @@ -460,6 +463,7 @@ static int intel_dg_mtd_erase(struct mtd_info *mtd, struct erase_info *info)
>>   	loff_t from;
>>   	size_t len;
>>   	size_t total_len;
>> +	int ret = 0;
>>   
>>   	if (WARN_ON(!nvm))
>>   		return -EINVAL;
>> @@ -474,20 +478,28 @@ static int intel_dg_mtd_erase(struct mtd_info *mtd, struct erase_info *info)
>>   	total_len = info->len;
>>   	addr = info->addr;
>>   
>> +	ret = pm_runtime_resume_and_get(mtd->dev.parent);
> on this, I really don't believe this is right and we should use
> the parent child relation ship in our favor and only have the mtd
> device to handle their own runtime pm...
I concur with Rodrigo. If the parent-child relationship is preserved, 
the parent will resume before the child, eliminating the need to 
explicitly wake the parent.
Please refer to https://docs.kernel.org/driver-api/pm/devices.html

The ordering of the device hierarchy is defined by the order in which 
devices get registered:
"a child can never be registered, probed or
resumed before its parent; "
and can’t be removed or suspended after that parent.
>
>> +	if (ret < 0) {
>> +		dev_err(&mtd->dev, "rpm: get failed %d\n", ret);
>> +		return ret;
>> +	}
>> +
>>   	guard(mutex)(&nvm->lock);
>>   
>>   	while (total_len > 0) {
>>   		if (!IS_ALIGNED(addr, SZ_4K) || !IS_ALIGNED(total_len, SZ_4K)) {
>>   			dev_err(&mtd->dev, "unaligned erase %llx %zx\n", addr, total_len);
>>   			info->fail_addr = addr;
>> -			return -ERANGE;
>> +			ret = -ERANGE;
>> +			goto out;
>>   		}
>>   
>>   		idx = idg_nvm_get_region(nvm, addr);
>>   		if (idx >= nvm->nregions) {
>>   			dev_err(&mtd->dev, "out of range");
>>   			info->fail_addr = MTD_FAIL_ADDR_UNKNOWN;
>> -			return -ERANGE;
>> +			ret = -ERANGE;
>> +			goto out;
>>   		}
>>   
>>   		from = addr - nvm->regions[idx].offset;
>> @@ -503,14 +515,18 @@ static int intel_dg_mtd_erase(struct mtd_info *mtd, struct erase_info *info)
>>   		if (bytes < 0) {
>>   			dev_dbg(&mtd->dev, "erase failed with %zd\n", bytes);
>>   			info->fail_addr += nvm->regions[idx].offset;
>> -			return bytes;
>> +			ret = bytes;
>> +			goto out;
>>   		}
>>   
>>   		addr += len;
>>   		total_len -= len;
>>   	}
>>   
>> -	return 0;
>> +out:
>> +	pm_runtime_mark_last_busy(mtd->dev.parent);
>> +	pm_runtime_put_autosuspend(mtd->dev.parent);
>> +	return ret;
>>   }
>>   
>>   static int intel_dg_mtd_read(struct mtd_info *mtd, loff_t from, size_t len,
>> @@ -539,17 +555,25 @@ static int intel_dg_mtd_read(struct mtd_info *mtd, loff_t from, size_t len,
>>   	if (len > nvm->regions[idx].size - from)
>>   		len = nvm->regions[idx].size - from;
>>   
>> +	ret = pm_runtime_resume_and_get(mtd->dev.parent);
>> +	if (ret < 0) {
>> +		dev_err(&mtd->dev, "rpm: get failed %zd\n", ret);
>> +		return ret;
>> +	}
>> +
>>   	guard(mutex)(&nvm->lock);
>>   
>>   	ret = idg_read(nvm, region, from, len, buf);
>>   	if (ret < 0) {
>>   		dev_dbg(&mtd->dev, "read failed with %zd\n", ret);
>> -		return ret;
>> +	} else {
>> +		*retlen = ret;
>> +		ret = 0;
>>   	}
>>   
>> -	*retlen = ret;
>> -
>> -	return 0;
>> +	pm_runtime_mark_last_busy(mtd->dev.parent);
>> +	pm_runtime_put_autosuspend(mtd->dev.parent);
>> +	return ret;
>>   }
>>   
>>   static int intel_dg_mtd_write(struct mtd_info *mtd, loff_t to, size_t len,
>> @@ -578,17 +602,25 @@ static int intel_dg_mtd_write(struct mtd_info *mtd, loff_t to, size_t len,
>>   	if (len > nvm->regions[idx].size - to)
>>   		len = nvm->regions[idx].size - to;
>>   
>> +	ret = pm_runtime_resume_and_get(mtd->dev.parent);
>> +	if (ret < 0) {
>> +		dev_err(&mtd->dev, "rpm: get failed %zd\n", ret);
>> +		return ret;
>> +	}
>> +
>>   	guard(mutex)(&nvm->lock);
>>   
>>   	ret = idg_write(nvm, region, to, len, buf);
>>   	if (ret < 0) {
>>   		dev_dbg(&mtd->dev, "write failed with %zd\n", ret);
>> -		return ret;
>> +	} else {
>> +		*retlen = ret;
>> +		ret = 0;
>>   	}
>>   
>> -	*retlen = ret;
>> -
>> -	return 0;
>> +	pm_runtime_mark_last_busy(mtd->dev.parent);
>> +	pm_runtime_put_autosuspend(mtd->dev.parent);
>> +	return ret;
>>   }
>>   
>>   static void intel_dg_nvm_release(struct kref *kref)
>> @@ -720,6 +752,17 @@ static int intel_dg_mtd_probe(struct auxiliary_device *aux_dev,
>>   		n++;
>>   	}
>>   
>> +	devm_pm_runtime_enable(device);
>> +
>> +	pm_runtime_set_autosuspend_delay(device, INTEL_DG_NVM_RPM_TIMEOUT);
>> +	pm_runtime_use_autosuspend(device);
>> +
>> +	ret = pm_runtime_resume_and_get(device);
>> +	if (ret < 0) {
>> +		dev_err(device, "rpm: get failed %d\n", ret);
>> +		goto err_norpm;
>> +	}
>> +
>>   	nvm->base = devm_ioremap_resource(device, &invm->bar);
>>   	if (IS_ERR(nvm->base)) {
>>   		dev_err(device, "mmio not mapped\n");
>> @@ -742,9 +785,12 @@ static int intel_dg_mtd_probe(struct auxiliary_device *aux_dev,
>>   
>>   	dev_set_drvdata(&aux_dev->dev, nvm);
>>   
>> +	pm_runtime_put(device);
>>   	return 0;
>>   
>>   err:
>> +	pm_runtime_put(device);
>> +err_norpm:
>>   	kref_put(&nvm->refcnt, intel_dg_nvm_release);
>>   	return ret;
>>   }
>> -- 
>> 2.43.0
>>

______________________________________________________
Linux MTD discussion mailing list
http://lists.infradead.org/mailman/listinfo/linux-mtd/