[U-Boot] [PATCH] dm: video: fix abuse of enum

[Simon Glass]

Hi Lothar,

On 7 July 2017 at 00:41, Lothar Waßmann <LW at karo-electronics.de> wrote:
> Hi,
>
> On Thu, 6 Jul 2017 12:22:52 +0000 Marcel Ziswiler wrote:
>> Dear Lothar
>>
>> On Thu, 2017-07-06 at 09:50 +0200, Lothar Waßmann wrote:
>> > Hi,
>> >
>> > On Wed, 5 Jul 2017 22:49:28 -0600 Simon Glass wrote:
>> > > Hi Lothar,
>> > >
>> > > On 23 June 2017 at 00:30, Lothar Waßmann <LW at karo-electronics.de>
>> > > wrote:
>> > > > Hi,
>> > > >
>> > > > On Wed, 21 Jun 2017 09:59:05 +0200 Lothar Waßmann wrote:
>> > > > > Hi,
>> > > > >
>> > > > > On Tue, 20 Jun 2017 12:26:29 -0600 Simon Glass wrote:
>> > > > > > Hi Lothar,
>> > > > > >
>> > > > > > On 20 June 2017 at 04:25, Lothar Waßmann <LW at karo-electronics
>> > > > > > .de> wrote:
>> > > > > > > LCD_MAX_WIDTH, LCD_MAX_HEIGHT and LCD_MAX_LSBPP are not
>> > > > > > > alternative
>> > > > > > > values for one specific variable, but unrelated entities
>> > > > > > > with distinct
>> > > > > > > purposes. There is no use defining them as values of an
>> > > > > > > 'enum'.
>> > > > > >
>> > > > > > Can you explain why #define is better? I prefer enum since
>> > > > > > they are a
>> > > > > > compiler construct instead of preprocessor (thus no need for
>> > > > > > brackets,
>> > > > > > no strange conversion things) and the debugger knows about
>> > > > > > them.
>> > > > > >
>> > > > >
>> > > > > An enum defines alternative values for one specific entity
>> > > > > (e.g.
>> > > > > clauses for a switch construct), but not a collection of
>> > > > > arbitrary data
>> > > > > items.
>> > > > >
>> > > > > > > The 'enum' construct would fail miserably for an LCD
>> > > > > > > controller that
>> > > > > > > has a square max. frame size (e.g. 4096x4096).
>> > > > > >
>> > > > > > What does this mean? I don't understand sorry.
>> > > > > >
>> > > > >
>> > > > > Try your enum with MAX_LCD_WITDH == MAC_LCD_HEIGHT.
>> > >
>> > > Can you please be explicit as to what the problem is? Sorry but I
>> > > don't understand what you are driving at. Do you have a test
>> > > program
>> > > which shows the problem?
>> > >
>> >
>> > You cannot have two different enum items with the same value!
>> > Thus:
>> > enum {
>> >     MAX_LCD_WIDTH = 4096,
>> >     MAX_LCD_HEIGHT = 4096,
>> > };
>> > won't compile.
>>
>> Says who?
>>
>> At least my gcc compilers even compile the following just fine:
>>
>> enum {
>>       MAX_LCD_WIDTH = 4096,
>>       MAX_LCD_HEIGHT = MAX_LCD_WIDTH,
>> };
>>
> Sorry, I was so locked in to the "normal" use of enum that I got
> confused.

OK I see, no worries.

I agree this is a borderline case, but I still prefer it :-)

Regards,
Simon