[PATCH net-next] r8169: improve interrupt handling

[PATCH net-next] r8169: improve interrupt handling

[Heiner Kallweit]

This patch improves few aspects of interrupt handling:
- update to current interrupt allocation API
  (use pci_alloc_irq_vectors() instead of deprecated pci_enable_msi())
- this implicitly will allocate a MSI-X interrupt if available
- get rid of flag RTL_FEATURE_MSI

Last but not least it enables a feature which was (I presume accidently)
disabled before. There are members of the RTL8169 family supporting MSI
(e.g. RTL8169SB), however MSI never got enabled because RTL_CFG_0 was
missing flag RTL_FEATURE_MSI.
An indicator for "accidently" is that statement "cfg2 |= MSIEnable;"
in rtl_try_msi() is dead code. cfg2 is used for chip versions <= 06
only and for all these chip versions RTL_FEATURE_MSI isn't set.

The patch works fine on a RTL8168evl (chip version 34).

The previously accidently disabled MSI support for the few members of
the old RTL8169 family supporting MSI isn't tested. The RTL8169SB
(chip version 04) I have at least still works in a PCI slot w/o MSI.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
 drivers/net/ethernet/realtek/r8169.c | 44 ++++++++++++++++--------------------
 1 file changed, 20 insertions(+), 24 deletions(-)

diff --git a/drivers/net/ethernet/realtek/r8169.c b/drivers/net/ethernet/realtek/r8169.c
index 96db3283e..4730db990 100644
--- a/drivers/net/ethernet/realtek/r8169.c
+++ b/drivers/net/ethernet/realtek/r8169.c
@@ -736,8 +736,7 @@ struct ring_info {
 };
 
 enum features {
-	RTL_FEATURE_MSI		= (1 << 0),
-	RTL_FEATURE_GMII	= (1 << 1),
+	RTL_FEATURE_GMII	= (1 << 0),
 };
 
 struct rtl8169_counters {
@@ -7847,7 +7846,7 @@ static int rtl8169_close(struct net_device *dev)
 
 	cancel_work_sync(&tp->wk.work);
 
-	free_irq(pdev->irq, dev);
+	pci_free_irq(pdev, 0, dev);
 
 	dma_free_coherent(&pdev->dev, R8169_RX_RING_BYTES, tp->RxDescArray,
 			  tp->RxPhyAddr);
@@ -7903,9 +7902,8 @@ static int rtl_open(struct net_device *dev)
 
 	rtl_request_firmware(tp);
 
-	retval = request_irq(pdev->irq, rtl8169_interrupt,
-			     (tp->features & RTL_FEATURE_MSI) ? 0 : IRQF_SHARED,
-			     dev->name, dev);
+	retval = pci_request_irq(pdev, 0, rtl8169_interrupt, NULL, dev,
+				 dev->name);
 	if (retval < 0)
 		goto err_release_fw_2;
 
@@ -8253,7 +8251,7 @@ static const struct rtl_cfg_info {
 		.region		= 2,
 		.align		= 8,
 		.event_slow	= SYSErr | LinkChg | RxOverflow,
-		.features	= RTL_FEATURE_GMII | RTL_FEATURE_MSI,
+		.features	= RTL_FEATURE_GMII,
 		.coalesce_info	= rtl_coalesce_info_8168_8136,
 		.default_ver	= RTL_GIGA_MAC_VER_11,
 	},
@@ -8263,32 +8261,32 @@ static const struct rtl_cfg_info {
 		.align		= 8,
 		.event_slow	= SYSErr | LinkChg | RxOverflow | RxFIFOOver |
 				  PCSTimeout,
-		.features	= RTL_FEATURE_MSI,
 		.coalesce_info	= rtl_coalesce_info_8168_8136,
 		.default_ver	= RTL_GIGA_MAC_VER_13,
 	}
 };
 
 /* Cfg9346_Unlock assumed. */
-static unsigned rtl_try_msi(struct rtl8169_private *tp,
-			    const struct rtl_cfg_info *cfg)
+static void rtl_alloc_irq(struct rtl8169_private *tp)
 {
 	void __iomem *ioaddr = tp->mmio_addr;
-	unsigned msi = 0;
 	u8 cfg2;
+	int ret;
 
-	cfg2 = RTL_R8(Config2) & ~MSIEnable;
-	if (cfg->features & RTL_FEATURE_MSI) {
-		if (pci_enable_msi(tp->pci_dev)) {
-			netif_info(tp, hw, tp->dev, "no MSI. Back to INTx.\n");
-		} else {
-			cfg2 |= MSIEnable;
-			msi = RTL_FEATURE_MSI;
-		}
+	ret = pci_alloc_irq_vectors(tp->pci_dev, 1, 1, PCI_IRQ_ALL_TYPES);
+	if (ret < 0) {
+		netif_err(tp, drv, tp->dev, "failed to allocate irq!\n");
+		return;
 	}
-	if (tp->mac_version <= RTL_GIGA_MAC_VER_06)
+
+	if (tp->mac_version <= RTL_GIGA_MAC_VER_06) {
+		RTL_W8(Cfg9346, Cfg9346_Unlock);
+		cfg2 = RTL_R8(Config2) & ~MSIEnable;
+		if (pci_dev_msi_enabled(tp->pci_dev))
+			cfg2 |= MSIEnable;
 		RTL_W8(Config2, cfg2);
-	return msi;
+		RTL_W8(Cfg9346, Cfg9346_Lock);
+	}
 }
 
 DECLARE_RTL_COND(rtl_link_list_ready_cond)
@@ -8497,9 +8495,7 @@ static int rtl_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
 	chipset = tp->mac_version;
 	tp->txd_version = rtl_chip_infos[chipset].txd_version;
 
-	RTL_W8(Cfg9346, Cfg9346_Unlock);
-	tp->features |= rtl_try_msi(tp, cfg);
-	RTL_W8(Cfg9346, Cfg9346_Lock);
+	rtl_alloc_irq(tp);
 
 	/* override BIOS settings, use userspace tools to enable WOL */
 	__rtl8169_set_wol(tp, 0);
-- 
2.16.2

Re: [PATCH net-next] r8169: improve interrupt handling

[Francois Romieu]

Heiner Kallweit <hkallweit1@gmail.com> :
[...]
> Last but not least it enables a feature which was (I presume accidently)
> disabled before. There are members of the RTL8169 family supporting MSI
> (e.g. RTL8169SB), however MSI never got enabled because RTL_CFG_0 was
> missing flag RTL_FEATURE_MSI.
> An indicator for "accidently" is that statement "cfg2 |= MSIEnable;"

The reality is more simple: it could had been removed.

> in rtl_try_msi() is dead code. cfg2 is used for chip versions <= 06
> only and for all these chip versions RTL_FEATURE_MSI isn't set.

On purpose:
1. mostly untested
2. MSI without MSI-X does not buy much
3. wrt 2., ok, it kills (yucky) plain old shared PCI irq (remember those ?)
   but I didn't end feeling that good about realtek MSI support on older
   chipsets to enable it any further

[...]
> diff --git a/drivers/net/ethernet/realtek/r8169.c b/drivers/net/ethernet/realtek/r8169.c
> index 96db3283e..4730db990 100644
> --- a/drivers/net/ethernet/realtek/r8169.c
> +++ b/drivers/net/ethernet/realtek/r8169.c
[...]
> -static unsigned rtl_try_msi(struct rtl8169_private *tp,
> -			    const struct rtl_cfg_info *cfg)
> +static void rtl_alloc_irq(struct rtl8169_private *tp)
>  {
[...]
> +	ret = pci_alloc_irq_vectors(tp->pci_dev, 1, 1, PCI_IRQ_ALL_TYPES);
> +	if (ret < 0) {
> +		netif_err(tp, drv, tp->dev, "failed to allocate irq!\n");
> +		return;
[...]
> @@ -8497,9 +8495,7 @@ static int rtl_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
>  	chipset = tp->mac_version;
>  	tp->txd_version = rtl_chip_infos[chipset].txd_version;
>  
> -	RTL_W8(Cfg9346, Cfg9346_Unlock);
> -	tp->features |= rtl_try_msi(tp, cfg);
> -	RTL_W8(Cfg9346, Cfg9346_Lock);
> +	rtl_alloc_irq(tp);

Happily proceeding after error. :o/

-- 
Ueimor

Re: [PATCH net-next] r8169: improve interrupt handling

[Heiner Kallweit]

Am 24.02.2018 um 02:35 schrieb Francois Romieu:
> Heiner Kallweit <hkallweit1@gmail.com> :
> [...]
>> Last but not least it enables a feature which was (I presume accidently)
>> disabled before. There are members of the RTL8169 family supporting MSI
>> (e.g. RTL8169SB), however MSI never got enabled because RTL_CFG_0 was
>> missing flag RTL_FEATURE_MSI.
>> An indicator for "accidently" is that statement "cfg2 |= MSIEnable;"
> 
> The reality is more simple: it could had been removed.
> 
>> in rtl_try_msi() is dead code. cfg2 is used for chip versions <= 06
>> only and for all these chip versions RTL_FEATURE_MSI isn't set.
> 
> On purpose:
> 1. mostly untested
> 2. MSI without MSI-X does not buy much
> 3. wrt 2., ok, it kills (yucky) plain old shared PCI irq (remember those ?)
>    but I didn't end feeling that good about realtek MSI support on older
>    chipsets to enable it any further
> 
Good to know, thanks for the feedback.
Then I'll change the patch to leave MSI disabled on old PCI chips.
Plus addressing your last comment.


> [...]
>> diff --git a/drivers/net/ethernet/realtek/r8169.c b/drivers/net/ethernet/realtek/r8169.c
>> index 96db3283e..4730db990 100644
>> --- a/drivers/net/ethernet/realtek/r8169.c
>> +++ b/drivers/net/ethernet/realtek/r8169.c
> [...]
>> -static unsigned rtl_try_msi(struct rtl8169_private *tp,
>> -			    const struct rtl_cfg_info *cfg)
>> +static void rtl_alloc_irq(struct rtl8169_private *tp)
>>  {
> [...]
>> +	ret = pci_alloc_irq_vectors(tp->pci_dev, 1, 1, PCI_IRQ_ALL_TYPES);
>> +	if (ret < 0) {
>> +		netif_err(tp, drv, tp->dev, "failed to allocate irq!\n");
>> +		return;
> [...]
>> @@ -8497,9 +8495,7 @@ static int rtl_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
>>  	chipset = tp->mac_version;
>>  	tp->txd_version = rtl_chip_infos[chipset].txd_version;
>>  
>> -	RTL_W8(Cfg9346, Cfg9346_Unlock);
>> -	tp->features |= rtl_try_msi(tp, cfg);
>> -	RTL_W8(Cfg9346, Cfg9346_Lock);
>> +	rtl_alloc_irq(tp);
> 
> Happily proceeding after error. :o/
>