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From:   Peter Chen <peter.chen@nxp.com>
To:     Macpaul Lin <macpaul.lin@mediatek.com>
CC:     Felipe Balbi <balbi@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Alan Stern <stern@rowland.harvard.edu>,
        Bart Van Assche <bvanassche@acm.org>,
        Mediatek WSD Upstream <wsd_upstream@mediatek.com>,
        Macpaul Lin <macpaul.lin@gmail.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>,
        "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
        "linux-mediatek@lists.infradead.org" 
        <linux-mediatek@lists.infradead.org>,
        Justin Hsieh <justinhsieh@google.com>,
        Hakieyin Hsieh <hakieyin@gmail.com>
Subject: Re: [PATCH] usb/gadget/function: introduce Built-in CDROM support
Thread-Topic: [PATCH] usb/gadget/function: introduce Built-in CDROM support
Thread-Index: AQHWPs9uyeBNKYlTkUGbGwgcbN1ORqjRRhwA
Date:   Wed, 10 Jun 2020 04:44:22 +0000
Message-ID: <20200610044446.GA8540@b29397-desktop>
References: <ejh@nvidia.com> <mchehab+samsung@kernel.org>
 <benh@kernel.crashing.org>
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On 20-06-10 10:32:29, Macpaul Lin wrote:
> Introduce Built-In CDROM (BICR) support.
> This feature depends on USB_CONFIGFS_MASS_STORAGE option.
>=20
> 1. Some settings and new function is introduced for BICR.
> 2. Some work around for adapting Android settings is intorduced as well.

%s/intorduced/introduced

> --- a/drivers/usb/gadget/function/f_mass_storage.c
> +++ b/drivers/usb/gadget/function/f_mass_storage.c
> @@ -315,6 +315,9 @@ struct fsg_common {
>  	void			*private_data;
> =20
>  	char inquiry_string[INQUIRY_STRING_LEN];
> +
> +	/* For build-in CDROM */
> +	u8 bicr;
>  };
> =20
>  struct fsg_dev {
> @@ -369,6 +372,10 @@ static void set_bulk_out_req_length(struct fsg_commo=
n *common,
>  	if (rem > 0)
>  		length +=3D common->bulk_out_maxpacket - rem;
>  	bh->outreq->length =3D length;
> +
> +	/* some USB 2.0 hardware requires this setting */
> +	if (IS_ENABLED(USB_CONFIGFS_BICR))
> +		bh->outreq->short_not_ok =3D 1;
>  }

Why not use fsg_common.bicr instead of MACRO?

Peter
> =20
> =20
> @@ -527,7 +534,16 @@ static int fsg_setup(struct usb_function *f,
>  				w_length !=3D 1)
>  			return -EDOM;
>  		VDBG(fsg, "get max LUN\n");
> -		*(u8 *)req->buf =3D _fsg_common_get_max_lun(fsg->common);
> +		if (IS_ENABLED(USB_CONFIGFS_BICR) && fsg->common->bicr) {
> +			/*
> +			 * When Built-In CDROM is enabled,
> +			 * we share only one LUN.
> +			 */
> +			*(u8 *)req->buf =3D 0;
> +		} else {
> +			*(u8 *)req->buf =3D _fsg_common_get_max_lun(fsg->common);
> +		}
> +		INFO(fsg, "get max LUN =3D %d\n", *(u8 *)req->buf);
> =20
>  		/* Respond with data/status */
>  		req->length =3D min((u16)1, w_length);
> @@ -1329,7 +1345,7 @@ static int do_start_stop(struct fsg_common *common)
>  	}
> =20
>  	/* Are we allowed to unload the media? */
> -	if (curlun->prevent_medium_removal) {
> +	if (!curlun->nofua && curlun->prevent_medium_removal) {
>  		LDBG(curlun, "unload attempt prevented\n");
>  		curlun->sense_data =3D SS_MEDIUM_REMOVAL_PREVENTED;
>  		return -EINVAL;
> @@ -2692,6 +2708,7 @@ int fsg_common_set_cdev(struct fsg_common *common,
>  	common->ep0 =3D cdev->gadget->ep0;
>  	common->ep0req =3D cdev->req;
>  	common->cdev =3D cdev;
> +	common->bicr =3D 0;
> =20
>  	us =3D usb_gstrings_attach(cdev, fsg_strings_array,
>  				 ARRAY_SIZE(fsg_strings));
> @@ -2895,6 +2912,33 @@ static void fsg_common_release(struct fsg_common *=
common)
>  		kfree(common);
>  }
> =20
> +#ifdef USB_CONFIGFS_BICR
> +ssize_t fsg_bicr_show(struct fsg_common *common, char *buf)
> +{
> +	return sprintf(buf, "%d\n", common->bicr);
> +}
> +
> +ssize_t fsg_bicr_store(struct fsg_common *common, const char *buf, size_=
t size)
> +{
> +	int ret;
> +
> +	ret =3D kstrtou8(buf, 10, &common->bicr);
> +	if (ret)
> +		return -EINVAL;
> +
> +	/* Set Lun[0] is a CDROM when enable bicr.*/
> +	if (!strcmp(buf, "1"))
> +		common->luns[0]->cdrom =3D 1;
> +	else {
> +		common->luns[0]->cdrom =3D 0;
> +		common->luns[0]->blkbits =3D 0;
> +		common->luns[0]->blksize =3D 0;
> +		common->luns[0]->num_sectors =3D 0;
> +	}
> +
> +	return size;
> +}
> +#endif
> =20
>  /*----------------------------------------------------------------------=
---*/
> =20
> @@ -3463,6 +3507,7 @@ void fsg_config_from_params(struct fsg_config *cfg,
>  		lun->ro =3D !!params->ro[i];
>  		lun->cdrom =3D !!params->cdrom[i];
>  		lun->removable =3D !!params->removable[i];
> +		lun->nofua =3D !!params->nofua[i];
>  		lun->filename =3D
>  			params->file_count > i && params->file[i][0]
>  			? params->file[i]
> diff --git a/drivers/usb/gadget/function/f_mass_storage.h b/drivers/usb/g=
adget/function/f_mass_storage.h
> index 3b8c4ce2a40a..7097e2ea5cc9 100644
> --- a/drivers/usb/gadget/function/f_mass_storage.h
> +++ b/drivers/usb/gadget/function/f_mass_storage.h
> @@ -140,5 +140,8 @@ void fsg_common_set_inquiry_string(struct fsg_common =
*common, const char *vn,
>  void fsg_config_from_params(struct fsg_config *cfg,
>  			    const struct fsg_module_parameters *params,
>  			    unsigned int fsg_num_buffers);
> -
> +#ifdef CONFIG_USB_CONFIGFS_BICR
> +ssize_t fsg_bicr_show(struct fsg_common *common, char *buf);
> +ssize_t fsg_bicr_store(struct fsg_common *common, const char *buf, size_=
t size);
> +#endif
>  #endif /* USB_F_MASS_STORAGE_H */
> diff --git a/drivers/usb/gadget/function/storage_common.c b/drivers/usb/g=
adget/function/storage_common.c
> index f7e6c42558eb..8fe96eeddf35 100644
> --- a/drivers/usb/gadget/function/storage_common.c
> +++ b/drivers/usb/gadget/function/storage_common.c
> @@ -441,6 +441,29 @@ ssize_t fsg_store_file(struct fsg_lun *curlun, struc=
t rw_semaphore *filesem,
>  		return -EBUSY;				/* "Door is locked" */
>  	}
> =20
> +	pr_notice("%s file=3D%s, count=3D%d, curlun->cdrom=3D%d\n",
> +			__func__, buf, (int)count, curlun->cdrom);
> +
> +	/*
> +	 * WORKAROUND for Android:
> +	 *   VOLD would clean the file path after switching to bicr.
> +	 *   So when the lun is being a CD-ROM a.k.a. BICR.
> +	 *   Don't clean the file path to empty.
> +	 */
> +	if (curlun->cdrom =3D=3D 1 && count =3D=3D 1)
> +		return count;
> +
> +	/*
> +	 * WORKAROUND: Should be closed the fsg lun for virtual cd-rom,
> +	 * when switch to other usb functions.
> +	 * Use the special keyword "off", because the init can
> +	 * not parse the char '\n' in rc file and write into the sysfs.
> +	 */
> +	if (count =3D=3D 3 &&
> +			buf[0] =3D=3D 'o' && buf[1] =3D=3D 'f' && buf[2] =3D=3D 'f' &&
> +			fsg_lun_is_open(curlun))
> +		((char *) buf)[0] =3D 0;
> +
>  	/* Remove a trailing newline */
>  	if (count > 0 && buf[count-1] =3D=3D '\n')
>  		((char *) buf)[count-1] =3D 0;		/* Ugh! */
> --=20
> 2.18.0

--=20

Thanks,
Peter Chen=