Re: [PATCH v13 5/5] usb: xhci: provide a debugfs hook for erasing rom

Greg Kroah-Hartman
2020-05-13T12:46:02Z

On Wed, May 13, 2020 at 03:36:19PM +0300, Mathias Nyman wrote:
> On 6.5.2020 9.00, Vinod Koul wrote:
> > run "echo 1 > /sys/kernel/debug/renesas-usb/rom_erase" to erase
> > firmware when driver is loaded.
> >
> > Subsequent init of driver shall reload the firmware
> >
> > Signed-off-by: Vinod Koul <vkoul@kernel.org>
> > ---
> > drivers/usb/host/xhci-pci-renesas.c | 33 +++++++++++++++++++++++++++++
> > 1 file changed, 33 insertions(+)
> >
> > diff --git a/drivers/usb/host/xhci-pci-renesas.c b/drivers/usb/host/xhci-pci-renesas.c
> > index f7d2445d30ec..fa32ec352dc8 100644
> > --- a/drivers/usb/host/xhci-pci-renesas.c
> > +++ b/drivers/usb/host/xhci-pci-renesas.c
> > @@ -2,6 +2,7 @@
> > /* Copyright (C) 2019-2020 Linaro Limited */
> >
> > #include <linux/acpi.h>
> > +#include <linux/debugfs.h>
> > #include <linux/firmware.h>
> > #include <linux/module.h>
> > #include <linux/pci.h>
> > @@ -170,6 +171,8 @@ static int renesas_fw_verify(const void *fw_data,
> > return 0;
> > }
> >
> > +static void debugfs_init(struct pci_dev *pdev);
> > +
> > static bool renesas_check_rom(struct pci_dev *pdev)
> > {
> > u16 rom_status;
> > @@ -183,6 +186,7 @@ static bool renesas_check_rom(struct pci_dev *pdev)
> > rom_status &= RENESAS_ROM_STATUS_ROM_EXISTS;
> > if (rom_status) {
> > dev_dbg(&pdev->dev, "External ROM exists\n");
> > + debugfs_init(pdev);
> > return true; /* External ROM exists */
> > }
> >
> > @@ -449,6 +453,34 @@ static void renesas_rom_erase(struct pci_dev *pdev)
> > dev_dbg(&pdev->dev, "ROM Erase... Done success\n");
> > }
> >
> > +static int debugfs_rom_erase(void *data, u64 value)
> > +{
> > + struct pci_dev *pdev = data;
> > +
> > + if (value == 1) {
> > + dev_dbg(&pdev->dev, "Userspace requested ROM erase\n");
> > + renesas_rom_erase(pdev);
> > + return 0;
> > + }
> > + return -EINVAL;
> > +}
> > +DEFINE_DEBUGFS_ATTRIBUTE(rom_erase_ops, NULL, debugfs_rom_erase, "%llu\n");
> > +
> > +static struct dentry *debugfs_root;
> > +
> > +static void debugfs_init(struct pci_dev *pdev)
> > +{
> > + debugfs_root = debugfs_create_dir("renesas_usb", NULL);
>
> This will create a renesas_usb directory right under debugfs root.
> xhci has its own struct dentry xhci_debugfs_root;
> Use that as parent instead

Ah, I misssed that, a follow-on patch can do this, right?

> Also note that debugs_create_dir() can fail, for example if debugfs isn't supported.

Doesn't matter, never check the result, just move on and all is fine :)

This logic is correct, no need for it to be changed.

thanks,

greg k-h