From: matthew.gerlach@linux.intel.com
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: hao.wu@intel.com, yilun.xu@intel.com, russell.h.weight@intel.com,
basheer.ahmed.muddebihal@intel.com, trix@redhat.com,
mdf@kernel.org, linux-fpga@vger.kernel.org,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
tianfei.zhang@intel.com, corbet@lwn.net,
gregkh@linuxfoundation.org, linux-serial@vger.kernel.org,
jirislaby@kernel.org, geert+renesas@glider.be,
niklas.soderlund+renesas@ragnatech.se, macro@orcam.me.uk,
johan@kernel.org, lukas@wunner.de,
kernel test robot <lkp@intel.com>
Subject: Re: [PATCH v3 4/4] tty: serial: 8250: add DFL bus driver for Altera 16550.
Date: Thu, 6 Oct 2022 10:00:43 -0700 (PDT) [thread overview]
Message-ID: <alpine.DEB.2.22.394.2210060940150.1988353@rhweight-WRK1> (raw)
In-Reply-To: <YzxRxo8jL7rB1+px@smile.fi.intel.com>
On Tue, 4 Oct 2022, Andy Shevchenko wrote:
> On Tue, Oct 04, 2022 at 07:37:18AM -0700, matthew.gerlach@linux.intel.com wrote:
>> From: Matthew Gerlach <matthew.gerlach@linux.intel.com>
>>
>> Add a Device Feature List (DFL) bus driver for the Altera
>> 16550 implementation of UART.
>
> ...
>
>> Reported-by: kernel test robot <lkp@intel.com>
>
> https://docs.kernel.org/process/submitting-patches.html?highlight=reported#using-reported-by-tested-by-reviewed-by-suggested-by-and-fixes
>
> "The Reported-by tag gives credit to people who find bugs and report them and it
> hopefully inspires them to help us again in the future. Please note that if the
> bug was reported in private, then ask for permission first before using the
> Reported-by tag. The tag is intended for bugs; please do not use it to credit
> feature requests."
>
The kernel test robot did find a bug in my v1 submission. I was missing
the static keyword for a function declaration. Should I remove the tag?
>
> ...
>
>> + if (!dfhv1_has_params(dfh_base)) {
>> + dev_err(dev, "missing required DFH parameters\n");
>> + return -EINVAL;
>> + }
>
> Why not use dev_err_probe() everywhere since this is called only at ->probe()
> stage?
I wasn't sure if using dev_err_probe() was correct, since the usage is
technically in a different function. Since the code is only called from
->probe(), and it is much cleaner, I'll switch to dev_err_probe()
everywhere
> > ...
>
>> + off = dfhv1_find_param(dfh_base, max, DFHv1_PARAM_ID_CLK_FRQ);
>> + if (off < 0) {
>> + dev_err(dev, "missing CLK_FRQ param\n");
>
>> + return -EINVAL;
>
> Why error code is being shadowed?
Definitely a mistake.
>
>> + }
>
> ...
>
>> + off = dfhv1_find_param(dfh_base, max, DFHv1_PARAM_ID_FIFO_LEN);
>> + if (off < 0) {
>> + dev_err(dev, "missing FIFO_LEN param\n");
>> + return -EINVAL;
>
> Ditto.
>
>> + }
>
> ...
>
>> + off = dfhv1_find_param(dfh_base, max, DFHv1_PARAM_ID_REG_LAYOUT);
>> + if (off < 0) {
>> + dev_err(dev, "missing REG_LAYOUT param\n");
>> + return -EINVAL;
>> + }
>
> Ditto.
>
> ...
>
>> + dev_dbg(dev, "UART_LAYOUT_ID width %lld shift %d\n",
>> + FIELD_GET(DFHv1_PARAM_ID_REG_WIDTH, v), (int)uart->port.regshift);
>
> Casting in printf() in kernel in 99% shows the wrong specifier in use. Try to
> select the best suitable one.
I will remove the casting and find the correct format specifier.
>
> ...
>
>> + dfh_base = devm_ioremap_resource(dev, &dfl_dev->mmio_res);
>> + if (IS_ERR(dfh_base))
>> + return PTR_ERR(dfh_base);
>> +
>> + res_size = resource_size(&dfl_dev->mmio_res);
>> +
>> + ret = dfl_uart_get_params(dev, dfh_base, res_size, &uart);
>
>> + devm_iounmap(dev, dfh_base);
>> + devm_release_mem_region(dev, dfl_dev->mmio_res.start, res_size);
>
> If it's temporary, may be you shouldn't even consider devm_ioremap_resource()
> to begin with? The devm_* release type of functions in 99% of the cases
> indicate of the abusing devm_.
I will change the code to call ioremap() and request_mem_region() directly
instead of the devm_ versions.
>
>> + if (ret < 0)
>> + return dev_err_probe(dev, ret, "failed uart feature walk\n");
>
> ...
>
>> + dev_info(dev, "serial8250_register_8250_port %d\n", dfluart->line);
>
> Why do we need this noise?
No, we do not need this noise.
>
> ...
>
>> + if (dfluart->line >= 0)
>
> When this can be false?
This can never be false. I will remove it.
>
>> + serial8250_unregister_port(dfluart->line);
>
> ...
>
>> +config SERIAL_8250_DFL
>> + tristate "DFL bus driver for Altera 16550 UART"
>> + depends on SERIAL_8250 && FPGA_DFL
>> + help
>> + This option enables support for a Device Feature List (DFL) bus
>> + driver for the Altera 16650 UART. One or more Altera 16650 UARTs
>> + can be instantiated in a FPGA and then be discovered during
>> + enumeration of the DFL bus.
>
> When m, what be the module name?
I see the file, kernel/drivers/tty/serial/8250/8250_dfl.ko, installed
into /lib/modules/... I also see "alias dfl:t0000f0024* 8250_dfl" in
modules.alias
>
> ...
>
>> obj-$(CONFIG_SERIAL_8250_FOURPORT) += 8250_fourport.o
>> obj-$(CONFIG_SERIAL_8250_ACCENT) += 8250_accent.o
>> obj-$(CONFIG_SERIAL_8250_BOCA) += 8250_boca.o
>> +obj-$(CONFIG_SERIAL_8250_DFL) += 8250_dfl.o
>
> This group of drivers for the 4 UARTs on the board or so, does FPGA belong to
> it? (Same Q, btw, for the Kconfig section. And yes, I know that some of the
> entries are not properly placed there and in Makefile.)
Since 8250_dfl results in its own module, and my kernel config doesn't
have FOURPORT, ACCENT, nor BOCA, I guess I don't understand the problem.
>
>> obj-$(CONFIG_SERIAL_8250_EXAR_ST16C554) += 8250_exar_st16c554.o
>> obj-$(CONFIG_SERIAL_8250_HUB6) += 8250_hub6.o
>> obj-$(CONFIG_SERIAL_8250_FSL) += 8250_fsl.o
>
> --
> With Best Regards,
> Andy Shevchenko
Thanks for the feedback.
>
>
>
next prev parent reply other threads:[~2022-10-06 17:02 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-04 14:37 [PATCH v3 0/4] Enhance definition of DFH and use enhancements for uart driver matthew.gerlach
2022-10-04 14:37 ` [PATCH v3 1/4] Documentation: fpga: dfl: Add documentation for DFHv1 matthew.gerlach
2022-10-05 11:05 ` Ilpo Järvinen
2022-10-10 17:34 ` matthew.gerlach
2022-10-04 14:37 ` [PATCH v3 2/4] fpga: dfl: Add DFHv1 Register Definitions matthew.gerlach
2022-10-04 14:55 ` Andy Shevchenko
2022-10-04 14:37 ` [PATCH v3 3/4] fpga: dfl: add basic support for DFHv1 matthew.gerlach
2022-10-04 15:11 ` Andy Shevchenko
2022-10-06 9:47 ` Xu Yilun
2022-10-10 15:34 ` matthew.gerlach
2022-10-05 10:30 ` Ilpo Järvinen
2022-10-07 18:35 ` matthew.gerlach
2022-10-06 9:27 ` Xu Yilun
2022-10-10 16:58 ` matthew.gerlach
2022-10-11 6:28 ` Xu Yilun
2022-10-12 0:31 ` matthew.gerlach
2022-10-04 14:37 ` [PATCH v3 4/4] tty: serial: 8250: add DFL bus driver for Altera 16550 matthew.gerlach
2022-10-04 15:31 ` Andy Shevchenko
2022-10-06 17:00 ` matthew.gerlach [this message]
2022-10-06 17:44 ` Andy Shevchenko
2022-10-06 22:24 ` matthew.gerlach
2022-10-07 9:15 ` Andy Shevchenko
2022-10-07 15:10 ` matthew.gerlach
2022-10-07 15:28 ` Andy Shevchenko
2022-10-05 10:47 ` Ilpo Järvinen
2022-10-06 21:47 ` matthew.gerlach
2022-10-10 14:53 ` Marco Pagani
2022-10-10 19:42 ` matthew.gerlach
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