diff mbox series

[v2,4/4] wifi: ath12k: Refactor data path cmem init

Message ID 20240409151415.1226109-5-quic_periyasa@quicinc.com
State Superseded
Headers show
Series wifi: ath12k: Refactor hardware cookie conversion | expand

Commit Message

Karthikeyan Periyasamy April 9, 2024, 3:14 p.m. UTC 
Move the data path Tx and Rx descriptor primary page table CMEM
configuration into a helper function. This will make the code more
scalable for configuring partner device in support of multi-device MLO.

Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.1.1-00188-QCAHKSWPL_SILICONZ-1
Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.0.c5-00481-QCAHMTSWPL_V1.0_V2.0_SILICONZ-3

Signed-off-by: Karthikeyan Periyasamy <quic_periyasa@quicinc.com>
Acked-by: Jeff Johnson <quic_jjohnson@quicinc.com>
---
 drivers/net/wireless/ath/ath12k/dp.c | 44 +++++++++++++++++++++++-----
 1 file changed, 37 insertions(+), 7 deletions(-)

Comments

Kalle Valo April 11, 2024, 9:45 a.m. UTC | #1 
Karthikeyan Periyasamy <quic_periyasa@quicinc.com> writes:

> Move the data path Tx and Rx descriptor primary page table CMEM
> configuration into a helper function. This will make the code more
> scalable for configuring partner device in support of multi-device MLO.
>
> Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.1.1-00188-QCAHKSWPL_SILICONZ-1
> Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.0.c5-00481-QCAHMTSWPL_V1.0_V2.0_SILICONZ-3
>
> Signed-off-by: Karthikeyan Periyasamy <quic_periyasa@quicinc.com>
> Acked-by: Jeff Johnson <quic_jjohnson@quicinc.com>

[...]

> +static void ath12k_dp_cmem_init(struct ath12k_base *ab,
> +				struct ath12k_dp *dp,
> +				enum ath12k_dp_desc_type type)
> +{
> +	u32 cmem_base;
> +	int i, start, end;
> +
> +	cmem_base = ab->qmi.dev_mem[ATH12K_QMI_DEVMEM_CMEM_INDEX].start;
> +
> +	switch (type) {
> +	case ATH12K_DP_TX_DESC:
> +		start = ATH12K_TX_SPT_PAGE_OFFSET;
> +		end = start + ATH12K_NUM_TX_SPT_PAGES;
> +		break;
> +	case ATH12K_DP_RX_DESC:
> +		start = ATH12K_RX_SPT_PAGE_OFFSET;
> +		end = start + ATH12K_NUM_RX_SPT_PAGES;
> +		break;
> +	default:
> +		ath12k_err(ab, "invalid descriptor type %d in cmem init\n", type);
> +		return;
> +	}
> +
> +	/* Write to PPT in CMEM */
> +	for (i = start; i < end; i++)
> +		ath12k_hif_write32(ab, cmem_base + ATH12K_PPT_ADDR_OFFSET(i),
> +				   dp->spt_info[i].paddr >> ATH12K_SPT_4K_ALIGN_OFFSET);
> +}

Here's a good example why I don't like functions returning void. How do
we handle the errors in this case?
Karthikeyan Periyasamy April 11, 2024, 10:07 a.m. UTC | #2 
On 4/11/2024 3:15 PM, Kalle Valo wrote:
> Karthikeyan Periyasamy <quic_periyasa@quicinc.com> writes:
> 
>> Move the data path Tx and Rx descriptor primary page table CMEM
>> configuration into a helper function. This will make the code more
>> scalable for configuring partner device in support of multi-device MLO.
>>
>> Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.1.1-00188-QCAHKSWPL_SILICONZ-1
>> Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.0.c5-00481-QCAHMTSWPL_V1.0_V2.0_SILICONZ-3
>>
>> Signed-off-by: Karthikeyan Periyasamy <quic_periyasa@quicinc.com>
>> Acked-by: Jeff Johnson <quic_jjohnson@quicinc.com>
> 
> [...]
> 
>> +static void ath12k_dp_cmem_init(struct ath12k_base *ab,
>> +				struct ath12k_dp *dp,
>> +				enum ath12k_dp_desc_type type)
>> +{
>> +	u32 cmem_base;
>> +	int i, start, end;
>> +
>> +	cmem_base = ab->qmi.dev_mem[ATH12K_QMI_DEVMEM_CMEM_INDEX].start;
>> +
>> +	switch (type) {
>> +	case ATH12K_DP_TX_DESC:
>> +		start = ATH12K_TX_SPT_PAGE_OFFSET;
>> +		end = start + ATH12K_NUM_TX_SPT_PAGES;
>> +		break;
>> +	case ATH12K_DP_RX_DESC:
>> +		start = ATH12K_RX_SPT_PAGE_OFFSET;
>> +		end = start + ATH12K_NUM_RX_SPT_PAGES;
>> +		break;
>> +	default:
>> +		ath12k_err(ab, "invalid descriptor type %d in cmem init\n", type);
>> +		return;
>> +	}
>> +
>> +	/* Write to PPT in CMEM */
>> +	for (i = start; i < end; i++)
>> +		ath12k_hif_write32(ab, cmem_base + ATH12K_PPT_ADDR_OFFSET(i),
>> +				   dp->spt_info[i].paddr >> ATH12K_SPT_4K_ALIGN_OFFSET);
>> +}
> 
> Here's a good example why I don't like functions returning void. How do
> we handle the errors in this case?
> 

sure, will handle the error case in the caller.
Jeff Johnson April 11, 2024, 3:20 p.m. UTC | #3 
On 4/11/2024 3:07 AM, Karthikeyan Periyasamy wrote:
> 
> 
> On 4/11/2024 3:15 PM, Kalle Valo wrote:
>> Karthikeyan Periyasamy <quic_periyasa@quicinc.com> writes:
>>
>>> Move the data path Tx and Rx descriptor primary page table CMEM
>>> configuration into a helper function. This will make the code more
>>> scalable for configuring partner device in support of multi-device MLO.
>>>
>>> Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.1.1-00188-QCAHKSWPL_SILICONZ-1
>>> Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.0.c5-00481-QCAHMTSWPL_V1.0_V2.0_SILICONZ-3
>>>
>>> Signed-off-by: Karthikeyan Periyasamy <quic_periyasa@quicinc.com>
>>> Acked-by: Jeff Johnson <quic_jjohnson@quicinc.com>
>>
>> [...]
>>
>>> +static void ath12k_dp_cmem_init(struct ath12k_base *ab,
>>> +				struct ath12k_dp *dp,
>>> +				enum ath12k_dp_desc_type type)
>>> +{
>>> +	u32 cmem_base;
>>> +	int i, start, end;
>>> +
>>> +	cmem_base = ab->qmi.dev_mem[ATH12K_QMI_DEVMEM_CMEM_INDEX].start;
>>> +
>>> +	switch (type) {
>>> +	case ATH12K_DP_TX_DESC:
>>> +		start = ATH12K_TX_SPT_PAGE_OFFSET;
>>> +		end = start + ATH12K_NUM_TX_SPT_PAGES;
>>> +		break;
>>> +	case ATH12K_DP_RX_DESC:
>>> +		start = ATH12K_RX_SPT_PAGE_OFFSET;
>>> +		end = start + ATH12K_NUM_RX_SPT_PAGES;
>>> +		break;
>>> +	default:
>>> +		ath12k_err(ab, "invalid descriptor type %d in cmem init\n", type);
>>> +		return;
>>> +	}
>>> +
>>> +	/* Write to PPT in CMEM */
>>> +	for (i = start; i < end; i++)
>>> +		ath12k_hif_write32(ab, cmem_base + ATH12K_PPT_ADDR_OFFSET(i),
>>> +				   dp->spt_info[i].paddr >> ATH12K_SPT_4K_ALIGN_OFFSET);
>>> +}
>>
>> Here's a good example why I don't like functions returning void. How do
>> we handle the errors in this case?
>>
> 
> sure, will handle the error case in the caller.
> 

this is a static function with one caller. the only error is the default case
which will never be hit. adding logic to return an error and then check it in
the caller seems like overkill. why not just WARN() in the default case since
this would be a logic error with newly added code?
Kalle Valo April 22, 2024, 12:04 p.m. UTC | #4 
Jeff Johnson <quic_jjohnson@quicinc.com> writes:

>>>> +	default:
>>>> +		ath12k_err(ab, "invalid descriptor type %d in cmem init\n", type);
>>>> +		return;
>>>> +	}
>>>> +
>>>> +	/* Write to PPT in CMEM */
>>>> +	for (i = start; i < end; i++)
>>>> +		ath12k_hif_write32(ab, cmem_base + ATH12K_PPT_ADDR_OFFSET(i),
>>>> + dp->spt_info[i].paddr >> ATH12K_SPT_4K_ALIGN_OFFSET);
>>>> +}
>>>
>>> Here's a good example why I don't like functions returning void. How do
>>> we handle the errors in this case?
>>>
>> 
>> sure, will handle the error case in the caller.
>> 
>
> this is a static function with one caller. the only error is the default case
> which will never be hit. adding logic to return an error and then check it in
> the caller seems like overkill. why not just WARN() in the default case since
> this would be a logic error with newly added code?

I think the software will be more robust then all errors are properly
handled in a uniform way. For example, will everyone notice the warning
message? What if the function is extended later and then the person
doesn't add any error handling "because it didn't have that even
earlier"? It's also a lot easier to review if error handling follows the
same style throughout the driver.

I didn't do any measurements but the overhead from this shouldn't be
that large, maybe few bytes in the binary and few new lines in the
source code. I think that's a reasonable price to pay from having more
robust software.

This is why I want to avoid void functions as much as possible. Of
course there also are good cases when to use void functions, like here:

https://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git/commit/?h=ath-next&id=6ef5b4c9598c928b3e2c4c4b543c81331941f136
Jeff Johnson April 22, 2024, 4:09 p.m. UTC | #5 
On 4/22/2024 5:04 AM, Kalle Valo wrote:
> Jeff Johnson <quic_jjohnson@quicinc.com> writes:
> 
>>>>> +	default:
>>>>> +		ath12k_err(ab, "invalid descriptor type %d in cmem init\n", type);
>>>>> +		return;
>>>>> +	}
>>>>> +
>>>>> +	/* Write to PPT in CMEM */
>>>>> +	for (i = start; i < end; i++)
>>>>> +		ath12k_hif_write32(ab, cmem_base + ATH12K_PPT_ADDR_OFFSET(i),
>>>>> + dp->spt_info[i].paddr >> ATH12K_SPT_4K_ALIGN_OFFSET);
>>>>> +}
>>>>
>>>> Here's a good example why I don't like functions returning void. How do
>>>> we handle the errors in this case?
>>>>
>>>
>>> sure, will handle the error case in the caller.
>>>
>>
>> this is a static function with one caller. the only error is the default case
>> which will never be hit. adding logic to return an error and then check it in
>> the caller seems like overkill. why not just WARN() in the default case since
>> this would be a logic error with newly added code?
> 
> I think the software will be more robust then all errors are properly
> handled in a uniform way. For example, will everyone notice the warning
> message? What if the function is extended later and then the person
> doesn't add any error handling "because it didn't have that even
> earlier"? It's also a lot easier to review if error handling follows the
> same style throughout the driver.

A large number of coding errors occur in exception paths. So minimizing the
number of exception paths decreases the opportunity for introducing these kind
of errors. So the real trick is making sure "all errors are properly handled
in a uniform way"

/jeff
diff mbox series

Patch

diff --git a/drivers/net/wireless/ath/ath12k/dp.c b/drivers/net/wireless/ath/ath12k/dp.c
index c8b2eb80b160..11d44e180b54 100644
--- a/drivers/net/wireless/ath/ath12k/dp.c
+++ b/drivers/net/wireless/ath/ath12k/dp.c
@@ -14,6 +14,11 @@ 
 #include "peer.h"
 #include "dp_mon.h"
 
+enum ath12k_dp_desc_type {
+	ATH12K_DP_TX_DESC,
+	ATH12K_DP_RX_DESC,
+};
+
 static void ath12k_dp_htt_htc_tx_complete(struct ath12k_base *ab,
 					  struct sk_buff *skb)
 {
@@ -1455,11 +1460,39 @@  static int ath12k_dp_cc_desc_init(struct ath12k_base *ab)
 	return 0;
 }
 
+static void ath12k_dp_cmem_init(struct ath12k_base *ab,
+				struct ath12k_dp *dp,
+				enum ath12k_dp_desc_type type)
+{
+	u32 cmem_base;
+	int i, start, end;
+
+	cmem_base = ab->qmi.dev_mem[ATH12K_QMI_DEVMEM_CMEM_INDEX].start;
+
+	switch (type) {
+	case ATH12K_DP_TX_DESC:
+		start = ATH12K_TX_SPT_PAGE_OFFSET;
+		end = start + ATH12K_NUM_TX_SPT_PAGES;
+		break;
+	case ATH12K_DP_RX_DESC:
+		start = ATH12K_RX_SPT_PAGE_OFFSET;
+		end = start + ATH12K_NUM_RX_SPT_PAGES;
+		break;
+	default:
+		ath12k_err(ab, "invalid descriptor type %d in cmem init\n", type);
+		return;
+	}
+
+	/* Write to PPT in CMEM */
+	for (i = start; i < end; i++)
+		ath12k_hif_write32(ab, cmem_base + ATH12K_PPT_ADDR_OFFSET(i),
+				   dp->spt_info[i].paddr >> ATH12K_SPT_4K_ALIGN_OFFSET);
+}
+
 static int ath12k_dp_cc_init(struct ath12k_base *ab)
 {
 	struct ath12k_dp *dp = &ab->dp;
 	int i, ret = 0;
-	u32 cmem_base;
 
 	INIT_LIST_HEAD(&dp->rx_desc_free_list);
 	spin_lock_init(&dp->rx_desc_lock);
@@ -1482,8 +1515,6 @@  static int ath12k_dp_cc_init(struct ath12k_base *ab)
 		return -ENOMEM;
 	}
 
-	cmem_base = ab->qmi.dev_mem[ATH12K_QMI_DEVMEM_CMEM_INDEX].start;
-
 	for (i = 0; i < dp->num_spt_pages; i++) {
 		dp->spt_info[i].vaddr = dma_alloc_coherent(ab->dev,
 							   ATH12K_PAGE_SIZE,
@@ -1500,12 +1531,11 @@  static int ath12k_dp_cc_init(struct ath12k_base *ab)
 			ret = -EINVAL;
 			goto free;
 		}
-
-		/* Write to PPT in CMEM */
-		ath12k_hif_write32(ab, cmem_base + ATH12K_PPT_ADDR_OFFSET(i),
-				   dp->spt_info[i].paddr >> ATH12K_SPT_4K_ALIGN_OFFSET);
 	}
 
+	ath12k_dp_cmem_init(ab, dp, ATH12K_DP_TX_DESC);
+	ath12k_dp_cmem_init(ab, dp, ATH12K_DP_RX_DESC);
+
 	ret = ath12k_dp_cc_desc_init(ab);
 	if (ret) {
 		ath12k_warn(ab, "HW CC desc init failed %d", ret);