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charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/12/2023 19:47, Markus Mayer wrote: > Add a best-effort probe function that tries all known DPFE versions to > see if one might actually work. This helps in cases where device tree > doesn't provide the proper version information for whatever reason. In So for incomplete DTS you now add elaborate, own, custom matching function. That's not how the code should work. > that case, the driver may still be able to register if one of the known > API versions ends up working. > > Caveat: we have to skip "v1" during our best effort attempts. This is > due to the fact that attempting a firmware download as required by v1 > will result in a memory access violation on anything but v1 hardware. > This would crash the kernel. Since we don't know the HW version, we need > to play it safe and skip v1. None of this commit explains what is real problem being solved. > > Signed-off-by: Markus Mayer > --- > drivers/memory/brcmstb_dpfe.c | 58 ++++++++++++++++++++++++++++++++++- > 1 file changed, 57 insertions(+), 1 deletion(-) > > diff --git a/drivers/memory/brcmstb_dpfe.c b/drivers/memory/brcmstb_dpfe.c > index 0b0a9b85b605..15f4ee3b8535 100644 > --- a/drivers/memory/brcmstb_dpfe.c > +++ b/drivers/memory/brcmstb_dpfe.c > @@ -879,6 +879,50 @@ static int brcmstb_dpfe_resume(struct platform_device *pdev) > return brcmstb_dpfe_download_firmware(priv); > } > > +static int brcmstb_dpfe_probe_best_effort(struct platform_device *pdev) > +{ > + const char versioned_compat[] = "brcm,dpfe-cpu-v"; > + const char v1_str[] = "-v1"; > + const struct of_device_id *matches; > + const struct dpfe_api *orig_dpfe_api; > + struct device *dev = &pdev->dev; > + struct brcmstb_dpfe_priv *priv; > + int ret = -ENODEV; > + > + priv = dev_get_drvdata(dev); > + orig_dpfe_api = priv->dpfe_api; > + matches = dev->driver->of_match_table; > + > + /* Loop over all compatible strings */ > + for (; matches->compatible[0]; matches++) { > + const char *compat = matches->compatible; > + /* Find the ones that start with "brcm,dpfe-cpu-v" */ > + if (strstr(compat, versioned_compat) == compat) { > + char *v1_ptr = strstr(compat, v1_str); > + /* > + * We must skip v1, since we don't know the hardware > + * version and attempting a firmware download on v2 and > + * newer would crash the kernel due to a memory access > + * violation. > + * We make sure to match "-v1" at the end of the string > + * only. > + */ > + if (v1_ptr && v1_ptr[sizeof(v1_str)] == '\0') > + continue; > + priv->dpfe_api = matches->data; > + /* Fingers crossed... */ > + ret = brcmstb_dpfe_download_firmware(priv); > + if (!ret) > + return 0; > + } > + } > + > + /* It didn't work, so let's clean up. */ > + priv->dpfe_api = orig_dpfe_api; > + > + return ret; > +} > + > static int brcmstb_dpfe_probe(struct platform_device *pdev) > { > struct device *dev = &pdev->dev; > @@ -923,8 +967,20 @@ static int brcmstb_dpfe_probe(struct platform_device *pdev) > } > > ret = brcmstb_dpfe_download_firmware(priv); > + if (ret && ret != -EPROBE_DEFER) { > + /* > + * If the information provided by Device Tree didn't work, let's > + * try all known version. Maybe one will work. I don't understand how this comment is related to downloading firmware. > + */ > + dev_warn(dev, > + "DPFE v%d didn't work, reverting to best-effort\n", > + priv->dpfe_api->version); > + dev_warn(dev, > + "Device Tree and / or the driver should be updated\n"); You are now introducing new warnings? NAK Best regards, Krzysztof