From: Marco Pagani <marpagan@redhat.com>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
matthew.gerlach@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, ilpo.jarvinen@linux.intel.com,
bagasdotme@gmail.com
Subject: Re: [PATCH v7 4/4] tty: serial: 8250: add DFL bus driver for Altera 16550.
Date: Wed, 21 Dec 2022 18:26:47 +0100 [thread overview]
Message-ID: <d34b021c-eec4-905e-f352-734db2d8338a@redhat.com> (raw)
In-Reply-To: <Y6HsQJQMDnHgTesF@smile.fi.intel.com>
On 2022-12-20 18:09, Andy Shevchenko wrote:
> On Tue, Dec 20, 2022 at 08:36:52AM -0800, 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.
>
> In general the code here looks good to me, but one thing to discuss due to
> comment to the previous patch(es).
>
> ...
>
>> + u64 *p;
>> +
>> + p = dfh_find_param(dfl_dev, DFHv1_PARAM_ID_CLK_FRQ);
>> + if (!p)
>> + return dev_err_probe(dev, -EINVAL, "missing CLK_FRQ param\n");
>> +
>> + p++;
>> + uart->port.uartclk = *p;
>
> So, here and the below is using always the second u64 from the returned data.
> Does it mean:
> - we always skip the first u64 from the returned buffer and hence... (see below)
> - we may actually return the second u64 as a plain number (not a pointer) from
> (an additional?) API? In such case we would not need to take care about this
> p++; lines here and there.
> - we have fixed length of the data, returned by find_param(), i.e. 2 u64 words?
>
I also had the impression that this method of getting and incrementing a pointer
to the beginning of the parameter block is a bit more error-prone than necessary.
Since parameter blocks are now standardized, wouldn't be easier and safer to wrap
the access logic into a helper function like:
u16 dfh_get_param_data(struct dfl_device *dfl_dev, u16 param_id, u64 *data)
that directly provides a copy of the parameter's data into a pointer provided by
the caller and returns the parameter version or an error if not found?
Thanks,
Marco
next prev parent reply other threads:[~2022-12-21 17:29 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-20 16:36 [PATCH v7 0/4] Enhance definition of DFH and use enhancements for UART driver matthew.gerlach
2022-12-20 16:36 ` [PATCH v7 1/4] Documentation: fpga: dfl: Add documentation for DFHv1 matthew.gerlach
2022-12-20 16:53 ` Andy Shevchenko
2022-12-21 16:52 ` matthew.gerlach
2022-12-20 16:36 ` [PATCH v7 2/4] fpga: dfl: Add DFHv1 Register Definitions matthew.gerlach
2022-12-20 16:54 ` Andy Shevchenko
2022-12-20 16:36 ` [PATCH v7 3/4] fpga: dfl: add basic support for DFHv1 matthew.gerlach
2022-12-20 17:03 ` Andy Shevchenko
2022-12-21 19:14 ` matthew.gerlach
2022-12-26 3:15 ` Xu Yilun
2022-12-31 20:46 ` matthew.gerlach
2023-01-03 4:22 ` Xu Yilun
2023-01-03 19:50 ` matthew.gerlach
2023-01-04 2:34 ` Xu Yilun
2022-12-21 11:58 ` Ilpo Järvinen
2022-12-21 22:29 ` matthew.gerlach
2022-12-20 16:36 ` [PATCH v7 4/4] tty: serial: 8250: add DFL bus driver for Altera 16550 matthew.gerlach
2022-12-20 17:09 ` Andy Shevchenko
2022-12-21 17:26 ` Marco Pagani [this message]
2022-12-21 19:52 ` Marco Pagani
2022-12-21 22:37 ` matthew.gerlach
2022-12-21 22:16 ` matthew.gerlach
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