Messages in this thread | | | Date | Tue, 3 Oct 2023 11:28:19 +0200 | From | Miquel Raynal <> | Subject | Re: [PATCH v2] mtd: rawnand: brcmnand: Initial exec_op implementation |
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Hi William,
william.zhang@broadcom.com wrote on Mon, 2 Oct 2023 12:57:01 -0700:
> Hi Miquel, > > On 10/02/2023 05:35 AM, Miquel Raynal wrote: > > Hi David, > > > > dregan@mail.com wrote on Sat, 30 Sep 2023 03:57:35 +0200: > > > >> Initial exec_op implementation for Broadcom STB, Broadband and iProc SoC > >> This adds exec_op and removes the legacy interface. > >> > >> Signed-off-by: David Regan <dregan@mail.com> > >> Reviewed-by: William Zhang <william.zhang@broadcom.com> > >> > >> --- > >> > > > > ... > > > >> +static int brcmnand_parser_exec_matched_op(struct nand_chip *chip, > >> + const struct nand_subop *subop) > >> +{ > >> + struct brcmnand_host *host = nand_get_controller_data(chip); > >> + struct brcmnand_controller *ctrl = host->ctrl; > >> + struct mtd_info *mtd = nand_to_mtd(chip); > >> + const struct nand_op_instr *instr = &subop->instrs[0]; > >> + unsigned int i; > >> + int ret = 0; > >> + > >> + for (i = 0; i < subop->ninstrs; i++) { > >> + instr = &subop->instrs[i]; > >> + > >> + if ((instr->type == NAND_OP_CMD_INSTR) && > >> + (instr->ctx.cmd.opcode == NAND_CMD_STATUS)) > >> + ctrl->status_cmd = 1; > >> + else if (ctrl->status_cmd && (instr->type == NAND_OP_DATA_IN_INSTR)) { > >> + /* > >> + * need to fake the nand device write protect because nand_base does a > >> + * nand_check_wp which calls nand_status_op NAND_CMD_STATUS which checks > >> + * that the nand is not write protected before an operation starts. > >> + * The problem with this is it's done outside exec_op so the nand is > >> + * write protected and this check will fail until the write or erase > >> + * or write back operation actually happens where we turn off wp. > >> + */ > >> + u8 *in; > >> + > >> + ctrl->status_cmd = 0; > >> + > >> + instr = &subop->instrs[i]; > >> + in = instr->ctx.data.buf.in; > >> + in[0] = brcmnand_status(host) | NAND_STATUS_WP; /* hide WP status */ > > > > I don't understand why you are faking the WP bit. If it's set, > > brcmnand_status() should return it and you should not care about it. If > > it's not however, can you please give me the path used when we have > > this issue? Either we need to modify the core or we need to provide > > additional helpers in this driver to circumvent the faulty path. > > The reason we have to hide wp status for status command is because > nand_base calls nand_check_wp at the very beginning of write and erase > function. This applies to both exec_op path and legacy path. With > Broadcom nand controller and most of our board design using the WP pin > and have it asserted by default, the nand_check_wp function will fail > and write/erase aborts. This workaround has been there before this > exec_op patch. > > I agree it is ugly and better to be addressed in the nand base code. And > I understand Broadcom's WP approach may sound a bit over cautious but we > want to make sure no spurious erase/write can happen under any > circumstance except software explicitly want to write and erase. WP is > standard nand chip pin and I think most the nand controller has that > that pin in the design too but it is possible it is not used and > bootloader can de-assert the pin and have a always-writable nand flash > for linux. So maybe we can add nand controller dts option "nand-use-wp". > If this property exist and set to 1, wp control is in use and nand > driver need to control the pin on/ff as needed when doing write and > erase function. Also nand base code should not call nand_check_wp when > wp is in use. Then we can remove the faking WP status workaround. > > > > >> + } else if (instr->type == NAND_OP_WAITRDY_INSTR) { > >> + ret = bcmnand_ctrl_poll_status(host, NAND_CTRL_RDY, NAND_CTRL_RDY, 0); > >> + if (ctrl->wp_cmd) { > >> + ctrl->wp_cmd = 0; > >> + brcmnand_wp(mtd, 1); > > > > This ideally should disappear. > > > Maybe we can have the destructive operation patch from Borris. > Controller driver still need to assert/deassert the pin if it uses nand > wp feature but at least it does not need to guess the op code.
Ah, yeah, I get it.
Please be my guest, you can revive this patch series (might need light tweaking, nothing big) and also take inspiration from it if necessary: https://github.com/bbrezillon/linux/commit/e612e1f2c69a33ac5f2c91d13669f0f172d58717 https://github.com/bbrezillon/linux/commit/4ec6f8d8d83f5aaca5d1877f02d48da96d41fcba https://github.com/bbrezillon/linux/commit/11b4acffd761c4928652d7028d19fcd6f45e4696
Thanks, Miquèl
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