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Date: Thu, 30 Jan 2020 22:57:52 +0100
From: Heiner Kallweit <hkallweit1@...il.com>
To: Robert Jones <rjones@...eworks.com>,
Sunil Goutham <sgoutham@...vell.com>,
Robert Richter <rrichter@...vell.com>,
David Miller <davem@...emloft.net>
Cc: Jakub Kicinski <kuba@...nel.org>,
Maciej Fijalkowski <maciej.fijalkowski@...el.com>,
linux-arm-kernel@...ts.infradead.org, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org, Tim Harvey <tharvey@...eworks.com>
Subject: Re: [PATCH net v2] net: thunderx: workaround BGX TX Underflow issue
On 30.01.2020 22:32, Robert Jones wrote:
> From: Tim Harvey <tharvey@...eworks.com>
>
> While it is not yet understood why a TX underflow can easily occur
> for SGMII interfaces resulting in a TX wedge. It has been found that
> disabling/re-enabling the LMAC resolves the issue.
>
I replied to your v1 and added some comments. Please see there.
> Signed-off-by: Tim Harvey <tharvey@...eworks.com>
> Reviewed-by: Robert Jones <rjones@...eworks.com>
> ---
> Changes in v2:
> - Changed bgx_register_intr() to a void return
> - Added pci_free_irq_vectors() calls to free irq if named/allocated
> - Use snprintf instead of sprintf for irq names
>
> drivers/net/ethernet/cavium/thunder/thunder_bgx.c | 59 +++++++++++++++++++++++
> drivers/net/ethernet/cavium/thunder/thunder_bgx.h | 9 ++++
> 2 files changed, 68 insertions(+)
>
> diff --git a/drivers/net/ethernet/cavium/thunder/thunder_bgx.c b/drivers/net/ethernet/cavium/thunder/thunder_bgx.c
> index c4f6ec0..cbf8596 100644
> --- a/drivers/net/ethernet/cavium/thunder/thunder_bgx.c
> +++ b/drivers/net/ethernet/cavium/thunder/thunder_bgx.c
> @@ -74,6 +74,7 @@ struct bgx {
> struct pci_dev *pdev;
> bool is_dlm;
> bool is_rgx;
> + char irq_name[7];
> };
>
> static struct bgx *bgx_vnic[MAX_BGX_THUNDER];
> @@ -1535,6 +1536,53 @@ static int bgx_init_phy(struct bgx *bgx)
> return bgx_init_of_phy(bgx);
> }
>
> +static irqreturn_t bgx_intr_handler(int irq, void *data)
> +{
> + struct bgx *bgx = (struct bgx *)data;
> + struct device *dev = &bgx->pdev->dev;
> + u64 status, val;
> + int lmac;
> +
> + for (lmac = 0; lmac < bgx->lmac_count; lmac++) {
> + status = bgx_reg_read(bgx, lmac, BGX_GMP_GMI_TXX_INT);
> + if (status & GMI_TXX_INT_UNDFLW) {
> + dev_err(dev, "BGX%d lmac%d UNDFLW\n", bgx->bgx_id,
> + lmac);
> + val = bgx_reg_read(bgx, lmac, BGX_CMRX_CFG);
> + val &= ~CMR_EN;
> + bgx_reg_write(bgx, lmac, BGX_CMRX_CFG, val);
> + val |= CMR_EN;
> + bgx_reg_write(bgx, lmac, BGX_CMRX_CFG, val);
> + }
> + /* clear interrupts */
> + bgx_reg_write(bgx, lmac, BGX_GMP_GMI_TXX_INT, status);
> + }
> +
> + return IRQ_HANDLED;
> +}
> +
> +static void bgx_register_intr(struct pci_dev *pdev)
> +{
> + struct bgx *bgx = pci_get_drvdata(pdev);
> + struct device *dev = &pdev->dev;
> + int num_vec, ret;
> +
> + /* Enable MSI-X */
> + num_vec = pci_msix_vec_count(pdev);
> + ret = pci_alloc_irq_vectors(pdev, num_vec, num_vec, PCI_IRQ_MSIX);
> + if (ret < 0) {
> + dev_err(dev, "Req for #%d msix vectors failed\n", num_vec);
> + return;
> + }
> + snprintf(bgx->irq_name, sizeof(bgx->irqname), "BGX%d", bgx->bgx_id);
> + ret = request_irq(pci_irq_vector(pdev, GMPX_GMI_TX_INT),
> + bgx_intr_handler, 0, bgx->irq_name, bgx);
> + if (ret) {
> + if (bgx->irq_name[0])
> + pci_free_irq_vectors(pdev);
> + }
> +}
> +
> static int bgx_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
> {
> int err;
> @@ -1604,6 +1652,8 @@ static int bgx_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
>
> bgx_init_hw(bgx);
>
> + bgx_register_intr(pdev);
> +
> /* Enable all LMACs */
> for (lmac = 0; lmac < bgx->lmac_count; lmac++) {
> err = bgx_lmac_enable(bgx, lmac);
> @@ -1614,12 +1664,18 @@ static int bgx_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
> bgx_lmac_disable(bgx, --lmac);
> goto err_enable;
> }
> +
> + /* enable TX FIFO Underflow interrupt */
> + bgx_reg_modify(bgx, lmac, BGX_GMP_GMI_TXX_INT_ENA_W1S,
> + GMI_TXX_INT_UNDFLW);
> }
>
> return 0;
>
> err_enable:
> bgx_vnic[bgx->bgx_id] = NULL;
> + if (bgx->irq_name[0])
> + pci_free_irq_vectors(pdev);
> err_release_regions:
> pci_release_regions(pdev);
> err_disable_device:
> @@ -1637,6 +1693,9 @@ static void bgx_remove(struct pci_dev *pdev)
> for (lmac = 0; lmac < bgx->lmac_count; lmac++)
> bgx_lmac_disable(bgx, lmac);
>
> + if (bgx->irq_name[0])
> + pci_free_irq_vectors(pdev);
> +
You free the vectors, however you should free the interrupt before.
And you could avoid having to free the vectors manually by switching
from pci_enable_device() to the managed version pcim_enable_device().
> bgx_vnic[bgx->bgx_id] = NULL;
> pci_release_regions(pdev);
> pci_disable_device(pdev);
> diff --git a/drivers/net/ethernet/cavium/thunder/thunder_bgx.h b/drivers/net/ethernet/cavium/thunder/thunder_bgx.h
> index 2588870..cdea493 100644
> --- a/drivers/net/ethernet/cavium/thunder/thunder_bgx.h
> +++ b/drivers/net/ethernet/cavium/thunder/thunder_bgx.h
> @@ -180,6 +180,15 @@
> #define BGX_GMP_GMI_TXX_BURST 0x38228
> #define BGX_GMP_GMI_TXX_MIN_PKT 0x38240
> #define BGX_GMP_GMI_TXX_SGMII_CTL 0x38300
> +#define BGX_GMP_GMI_TXX_INT 0x38500
> +#define BGX_GMP_GMI_TXX_INT_W1S 0x38508
> +#define BGX_GMP_GMI_TXX_INT_ENA_W1C 0x38510
> +#define BGX_GMP_GMI_TXX_INT_ENA_W1S 0x38518
> +#define GMI_TXX_INT_PTP_LOST BIT_ULL(4)
> +#define GMI_TXX_INT_LATE_COL BIT_ULL(3)
> +#define GMI_TXX_INT_XSDEF BIT_ULL(2)
> +#define GMI_TXX_INT_XSCOL BIT_ULL(1)
> +#define GMI_TXX_INT_UNDFLW BIT_ULL(0)
>
> #define BGX_MSIX_VEC_0_29_ADDR 0x400000 /* +(0..29) << 4 */
> #define BGX_MSIX_VEC_0_29_CTL 0x400008
>
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