[{"id":3676245,"web_url":"http://patchwork.ozlabs.org/comment/3676245/","msgid":"<2eee9241-8910-431a-9305-b5919937c826@kernel.org>","list_archive_url":null,"date":"2026-04-12T07:41:07","subject":"Re: [PATCH 3/3] ata: libata-scsi: probe additional LUNs for multi-LUN\n ATAPI devices","submitter":{"id":86188,"url":"http://patchwork.ozlabs.org/api/people/86188/","name":"Damien Le Moal","email":"dlemoal@kernel.org"},"content":"On 4/9/26 23:05, Phil Pemberton wrote:\n> Some ATAPI devices (e.g. the Panasonic PD/CD combo drives) implement\n> multiple logical units. For instance the aforementioned PD/CD has a CD\n> drive on LUN 0 and the rewritable Phase-change Dual (PD) block device on\n> LUN 1.\n> \n> ata_scsi_scan_host() previously only scanned LUN 0 via\n> __scsi_add_device(). With the multi-LUN work now in place, extend this\n> scan to probe for additional LUNs on devices which have BLIST_FORCELUN\n> set in the SCSI device info table.\n> \n> Scanning stops when __scsi_add_device() fails, or the device reports\n> device type 0x1f (unknown or no device type). The PD drive returns this\n> for unimplemented LUNs.\n> \n> The aforementioned BLIST_FORCELUN guard prevents non-multilun devices\n> from being affected.\n> \n> Tested with a Panasonic LF-1195C PD/CD with Compaq firmware, which now\n> correctly enumerates as a CD drive (sr) and PD optical drive (sd).\n> \n> Also tested with a LITE-ON iHAS124 DVD drive, which has a single LUN and\n> ignores the LUN parameter in the CDB. As a result, without the\n> BLIST_FORCELUN guard, this drive would pop up as eight separate devices.\n> \n> Assisted-by: Claude:claude-opus-4-6\n> Signed-off-by: Phil Pemberton \n> ---\n> drivers/ata/libata-scsi.c | 29 +++++++++++++++++++++++++++++\n> 1 file changed, 29 insertions(+)\n> \n> diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c\n> index dc6829e60fb3..0a7ce44118fe 100644\n> --- a/drivers/ata/libata-scsi.c\n> +++ b/drivers/ata/libata-scsi.c\n> @@ -4732,6 +4732,35 @@ void ata_scsi_scan_host(struct ata_port *ap, int sync)\n> \t\t\tif (!IS_ERR(sdev)) {\n> \t\t\t\tdev->sdev = sdev;\n> \t\t\t\tata_scsi_assign_ofnode(dev, ap);\n> +\t\t\t\t/*\n> +\t\t\t\t * Multi-LUN ATAPI devices (e.g. PD/CD combo\n> +\t\t\t\t * drives) are flagged BLIST_FORCELUN in\n> +\t\t\t\t * scsi_devinfo. Probe additional LUNs when\n> +\t\t\t\t * the flag is set.\n> +\t\t\t\t */\n> +\t\t\t\tif (dev->class == ATA_DEV_ATAPI &&\n> +\t\t\t\t (sdev->sdev_bflags & BLIST_FORCELUN)) {\n> +\t\t\t\t\tu64 lun;\n> +\n> +\t\t\t\t\tfor (lun = 1; lun < ap->scsi_host->max_lun;\n> +\t\t\t\t\t lun++) {\n> +\t\t\t\t\t\tstruct scsi_device *extra;\n> +\n> +\t\t\t\t\t\textra = __scsi_add_device(\n> +\t\t\t\t\t\t\tap->scsi_host,\n> +\t\t\t\t\t\t\tchannel, id, lun,\n> +\t\t\t\t\t\t\tNULL);\n> +\t\t\t\t\t\tif (IS_ERR(extra))\n> +\t\t\t\t\t\t\tbreak;\n> +\t\t\t\t\t\t/* PDT 0x1f: no device type */\n> +\t\t\t\t\t\tif (extra->type == 0x1f) {\n> +\t\t\t\t\t\t\tscsi_remove_device(extra);\n> +\t\t\t\t\t\t\tscsi_device_put(extra);\n> +\t\t\t\t\t\t\tbreak;\n> +\t\t\t\t\t\t}\n> +\t\t\t\t\t\tscsi_device_put(extra);\n> +\t\t\t\t\t}\n> +\t\t\t\t}\n\nIt would be a lot nicer and more readable to have this hunk as a helper\nfunction, e.g.: ata_scsi_scan_atapi_luns().\n\n> \t\t\t\tscsi_device_put(sdev);\n> \t\t\t} else {\n> \t\t\t\tdev->sdev = NULL;","headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linux-ide@vger.kernel.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256\n header.s=k20201202 header.b=BI9rAeLY;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=172.232.135.74; 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charset=UTF-8","Content-Transfer-Encoding":"7bit"}}]