On Thu, Jul 30, 2020 at 11:09 AM Arnd Bergmann <[email protected]> wrote: > > On Thu, Jul 30, 2020 at 2:21 PM Daniel Gutson <[email protected]> wrote: > > El jue., 30 jul. 2020 2:31 a. m., Greg Kroah-Hartman > > <[email protected]> escribió: > >> > >> Again, module parameters are working on a per-chunk-of-code basis, while > >> you want to work on a per-device basis, > > > > > > I think there is a misunderstanding. What I want is to control (turn on or > > off) is a very specific code snippet that provides the "functionality" of > > trying to turn the chip writable. The rest of the device driver is fine. > > I assume that the one that doesn't understand is me. > > > > I looked at the source code again and found that the existing module > parameter applies to both the platform and pci device front-ends, both > of which go through > > /* Prevent writes if not explicitly enabled */ > if (!ispi->writeable || !writeable) > ispi->nor.mtd.flags &= ~MTD_WRITEABLE; >
I think you missed https://elixir.bootlin.com/linux/latest/source/drivers/mtd/spi-nor/controllers/intel-spi-pci.c#L44 /* Try to make the chip read/write */ pci_read_config_dword(pdev, BCR, &bcr); if (!(bcr & BCR_WPD)) { bcr |= BCR_WPD; pci_write_config_dword(pdev, BCR, bcr); pci_read_config_dword(pdev, BCR, &bcr); } in the probe function, and is executed always and unconditionally. /* Try to make the chip read/write */ pci_read_config_dword(pdev, BCR, &bcr); if (!(bcr & BCR_WPD)) { bcr |= BCR_WPD; pci_write_config_dword(pdev, BCR, bcr); pci_read_config_dword(pdev, BCR, &bcr); } > Setting the PCI device writable in hardware makes it possible to > actually write to it *only* if the module parameter is also set to '1'. > One might disagree with that design, but I don't think your patch > would make it any better, it just means one would have to set > two module parameters instead of one. > > Arnd -- Daniel Gutson Argentina Site Director Enginieering Director Eclypsium Below The Surface: Get the latest threat research and insights on firmware and supply chain threats from the research team at Eclypsium. https://eclypsium.com/research/#threatreport
