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Message-ID: <14c200b4573b4a60af14b37861ca1727@realtek.com>
Date: Mon, 6 May 2024 11:32:38 +0000
From: Justin Lai <justinlai0215@...ltek.com>
To: Simon Horman <horms@...nel.org>
CC: "kuba@...nel.org" <kuba@...nel.org>,
"davem@...emloft.net"
<davem@...emloft.net>,
"edumazet@...gle.com" <edumazet@...gle.com>,
"pabeni@...hat.com" <pabeni@...hat.com>,
"linux-kernel@...r.kernel.org"
<linux-kernel@...r.kernel.org>,
"netdev@...r.kernel.org"
<netdev@...r.kernel.org>,
"andrew@...n.ch" <andrew@...n.ch>,
"jiri@...nulli.us" <jiri@...nulli.us>,
Ping-Ke Shih <pkshih@...ltek.com>, Larry Chiu <larry.chiu@...ltek.com>
Subject: RE: [PATCH net-next v17 01/13] rtase: Add pci table supported in this module
>
>
> On Thu, May 02, 2024 at 05:18:35PM +0800, Justin Lai wrote:
> > Add pci table supported in this module, and implement pci_driver
> > function to initialize this driver, remove this driver, or shutdown this driver.
> >
> > Signed-off-by: Justin Lai <justinlai0215@...ltek.com>
>
> ...
>
> > diff --git a/drivers/net/ethernet/realtek/rtase/rtase_main.c
> > b/drivers/net/ethernet/realtek/rtase/rtase_main.c
> > new file mode 100644
> > index 000000000000..5ddb5f7abfe9
> > --- /dev/null
> > +++ b/drivers/net/ethernet/realtek/rtase/rtase_main.c
> > @@ -0,0 +1,618 @@
> > +// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
> > +/*
> > + * rtase is the Linux device driver released for Realtek Automotive
> > +Switch
> > + * controllers with PCI-Express interface.
> > + *
> > + * Copyright(c) 2023 Realtek Semiconductor Corp.
> > + *
> > + * Below is a simplified block diagram of the chip and its relevant
> interfaces.
> > + *
> > + * *************************
> > + * * *
> > + * * CPU network device *
> > + * * *
> > + * * +-------------+ *
> > + * * | PCIE Host | *
> > + * ***********++************
> > + * ||
> > + * PCIE
> > + * ||
> > + * ********************++**********************
> > + * * | PCIE Endpoint | *
> > + * * +---------------+ *
> > + * * | GMAC | *
> > + * * +--++--+ Realtek *
> > + * * || RTL90xx Series *
> > + * * || *
> > + * * +-------------++----------------+ *
> > + * * | | MAC | | *
> > + * * | +-----+ | *
> > + * * | | *
> > + * * | Ethernet Switch Core | *
> > + * * | | *
> > + * * | +-----+ +-----+ | *
> > + * * | | MAC |...........| MAC | | *
> > + * * +---+-----+-----------+-----+---+ *
> > + * * | PHY |...........| PHY | *
> > + * * +--++-+ +--++-+ *
> > + * *************||****************||***********
>
> Thanks for the diagram, I like it a lot :)
>
Thank you for your like :)
> > + *
> > + * The block of the Realtek RTL90xx series is our entire chip
> > + architecture,
> > + * the GMAC is connected to the switch core, and there is no PHY in
> between.
> > + * In addition, this driver is mainly used to control GMAC, but does
> > + not
> > + * control the switch core, so it is not the same as DSA.
> > + */
>
> ...
>
> > +static int rtase_alloc_msix(struct pci_dev *pdev, struct
> > +rtase_private *tp) {
> > + int ret;
> > + u16 i;
> > +
> > + memset(tp->msix_entry, 0x0, RTASE_NUM_MSIX * sizeof(struct
> > + msix_entry));
> > +
> > + for (i = 0; i < RTASE_NUM_MSIX; i++)
> > + tp->msix_entry[i].entry = i;
> > +
> > + ret = pci_enable_msix_exact(pdev, tp->msix_entry, tp->int_nums);
> > + if (!ret) {
>
> In Linux Networking code it is an idiomatic practice to keep handle errors in
> branches and use the main path of execution for the non error path.
>
> In this case I think that would look a bit like this:
>
> ret = pci_enable_msix_exact(pdev, tp->msix_entry, tp->int_nums);
> if (ret)
> return ret;
>
> ...
>
> return 0;
>
> > +
> > + for (i = 0; i < tp->int_nums; i++)
> > + tp->int_vector[i].irq = pci_irq_vector(pdev, i);
>
> pci_irq_vector() can fail, should that be handled here?
Thank you for your feedback, I will confirm this part again.
>
> > + }
> > +
> > + return ret;
> > +}
> > +
> > +static int rtase_alloc_interrupt(struct pci_dev *pdev,
> > + struct rtase_private *tp) {
> > + int ret;
> > +
> > + ret = rtase_alloc_msix(pdev, tp);
> > + if (ret) {
> > + ret = pci_enable_msi(pdev);
> > + if (ret)
> > + dev_err(&pdev->dev,
> > + "unable to alloc interrupt.(MSI)\n");
>
> If an error occurs then it is a good practice to unwind resource allocations
> made within the context of this function call, as this leads to more symmetric
> unwind paths in callers.
>
> In this case I think any resources consumed by rtase_alloc_msix() should be
> released if pci_enable_msi fails. Probably using a goto label is appropriate
> here.
>
> Likewise, I suggest that similar logic applies to errors within
> rtase_alloc_msix().
>
Since msi will be enabled only when msix enable fails, when pci_enable_msi fails,
there will be no problem of msix-related resources needing to be released,
because the msix interrupt has not been successfully allocated.
> > + else
> > + tp->sw_flag |= RTASE_SWF_MSI_ENABLED;
> > + } else {
> > + tp->sw_flag |= RTASE_SWF_MSIX_ENABLED;
> > + }
> > +
> > + return ret;
> > +}
>
> ...
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