Re: [PATCH] cdrom: support Beurer GL50 evo CD-on-a-chip devices.

[Jens Axboe <axboe@kernel.dk>]

On 11/11/19 6:29 AM, Diego Elio Pettenò wrote:
> The Beurer GL50 evo uses a Cygnal/Cypress-manufactured CD-on-a-chip that
> only accepts a subset of SCSI commands.
> 
> Most of the not-implemented commands are fine to fail, but a few,
> particularly around the MMC or Audio commands, will put the device into an
> unrecoverable state, so they need to be avoided at all costs.
> 
> In addition to adding a new vendor entry to sr_vendor, this required gating
> a few functions in the cdrom driver to not even try sending the command
> when the capability is not present.

This is pretty horrible, but not really your fault. Just one minor note:

> @@ -1162,7 +1168,9 @@ int cdrom_open(struct cdrom_device_info *cdi, struct block_device *bdev,
>   		ret = open_for_data(cdi);
>   		if (ret)
>   			goto err;
> -		cdrom_mmc3_profile(cdi);
> +		if (CDROM_CAN(CDC_GENERIC_PACKET)) {
> +			cdrom_mmc3_profile(cdi);
> +		}
>   		if (mode & FMODE_WRITE) {
>   			ret = -EROFS;
>   			if (cdrom_open_write(cdi))

Just make that:

		if (CDROM_CAN(CDC_GENERIC_PACKET))
			cdrom_mmc3_profile(cdi);

And you probably want to split this patch into two, one with the
necessary changes to cdrom.c, and one that adds the Beuer device to
sr_vendor.c.

-- 
Jens Axboe